Add GET_CONTENT picker support, fix account/login bugs, restyle selection UI

- Let Noo be picked as a source (Files + Photos) by other apps' native
  file/photo pickers via Android's GET_CONTENT intent, mirroring the
  existing "Share to Noo" plumbing: MainActivity.kt/PickIntentService/
  PickRequest, ServerProvider.pickRequest/confirmPick/cancelPick, and
  pick-mode tap handling in FilesView/PhotosView. While picking, the
  bottom nav and MoreTabsButton are restricted to Files/Photos only.
- Fix two account bugs: testConnection() failures no longer delete a
  still-valid stored app password (only an actual 401 does), and
  switchAccount() now retries a nominally-active-but-logged-out account
  instead of no-op'ing - both were silently locking users out of "Continue
  as" with no way back in except removing and re-adding the account
  (now exposed via login_view.dart's inline remove button).
- Fix the login WebView: clear cookies before every load so "Add Account"
  can't silently reuse an existing session, and push it as a
  non-animated route to avoid a known WebView-as-PlatformView black-screen-
  on-pop issue under Impeller.
- Redesign the Files/Photos selection toolbar to take over the top app bar
  entirely (SyncedHeaderScaffold.selectionBar) instead of sitting as a
  second bar under the controls row, with a horizontally-scrollable,
  uniformly-colored actions row and the same one-shot scroll-hint nudge
  the controls row uses.
- Redesign ShareUploadView to share the same SyncedHeaderScaffold chrome
  as every tab, with the uploading-file summary (marqueed via the new
  shared MarqueeTitle widget) and upload button grouped into one
  rounded/elevated bottom sheet.
- Restyle ShareSheet to open on the same DetailsHeader every other
  per-item sheet uses, and fix a couple of small design-language drifts
  (hardcoded text style, a non-rounded icon).
- Settings' account card: icon buttons with tooltips instead of text
  buttons for refresh/logout/remove, divider removed.

lib/widgets/details/details_sheet.dart

@@ -73,13 +73,25 @@ class DetailsSheet extends StatelessWidget {
   }
 }
 
-/// Icon/name/size/date row shared by [DetailsSheet] and the media viewer's
+/// Icon/name/size/date row shared by [DetailsSheet], the media viewer's
 /// collapsed "peek" state (which shows just this, before the user drags the
-/// sheet open far enough to reveal the tabs).
+/// sheet open far enough to reveal the tabs), and [ShareSheet]'s own title
+/// (so every per-item bottom sheet opens on the same header instead of
+/// [ShareSheet] alone using a bare title `Text`).
 class DetailsHeader extends StatelessWidget {
   final NextcloudItem item;
 
-  const DetailsHeader({super.key, required this.item});
+  /// Defaults to this widget's own standalone inset ([DetailsSheet]); a
+  /// caller whose surrounding scroll view already applies horizontal
+  /// padding (e.g. [ShareSheet]'s `ListView`) should pass a padding with
+  /// zero left/right to avoid doubling it up.
+  final EdgeInsetsGeometry padding;
+
+  const DetailsHeader({
+    super.key,
+    required this.item,
+    this.padding = const EdgeInsets.fromLTRB(20, 12, 20, 8),
+  });
 
   @override
   Widget build(BuildContext context) {
@@ -87,7 +99,7 @@ class DetailsHeader extends StatelessWidget {
     final colorScheme = theme.colorScheme;
 
     return Padding(
-      padding: const EdgeInsets.fromLTRB(20, 12, 20, 8),
+      padding: padding,
       child: Row(
         children: [
           Container(

lib/widgets/marquee_title.dart

@@ -0,0 +1,49 @@
+import 'package:flutter/material.dart';
+import 'package:marquee/marquee.dart';
+
+/// A plain, single-line ellipsized [Text] for content that fits, or an
+/// auto-scrolling [Marquee] for text too long for the available width -
+/// measured once via [TextPainter] rather than always marqueeing, so short
+/// text just sits still like normal.
+class MarqueeTitle extends StatelessWidget {
+  final String text;
+  final TextStyle? style;
+
+  const MarqueeTitle({super.key, required this.text, required this.style});
+
+  @override
+  Widget build(BuildContext context) {
+    return LayoutBuilder(
+      builder: (context, constraints) {
+        final painter = TextPainter(
+          text: TextSpan(text: text, style: style),
+          maxLines: 1,
+          textDirection: Directionality.of(context),
+        )..layout(maxWidth: double.infinity);
+
+        if (painter.width <= constraints.maxWidth) {
+          return Text(
+            text,
+            maxLines: 1,
+            overflow: TextOverflow.ellipsis,
+            style: style,
+          );
+        }
+
+        return SizedBox(
+          height: painter.height,
+          child: Marquee(
+            text: text,
+            style: style,
+            blankSpace: 48,
+            velocity: 30,
+            startPadding: 0,
+            pauseAfterRound: const Duration(seconds: 1),
+            fadingEdgeStartFraction: 0.1,
+            fadingEdgeEndFraction: 0.15,
+          ),
+        );
+      },
+    );
+  }
+}

lib/widgets/more_tabs_button.dart

@@ -15,6 +15,13 @@ class MoreTabsButton extends StatelessWidget {
   Widget build(BuildContext context) {
     final provider = context.watch<ServerProvider>();
 
+    // While picking (another app's GET_CONTENT request), MainShellView
+    // already restricts the bottom nav to Files/Photos - this button would
+    // otherwise be the one remaining way to reach a tab that isn't a valid
+    // pick source (Trash, Shares, ...), so it hides entirely rather than
+    // just disabling.
+    if (provider.isPicking) return const SizedBox.shrink();
+
     return PopupMenuButton<AppTab>(
       icon: const Icon(Icons.apps_rounded),
       tooltip: 'More tabs',

lib/widgets/share_sheet.dart

@@ -5,6 +5,7 @@ import '../models/nextcloud_item.dart';
 import '../models/nextcloud_share.dart';
 import '../models/nextcloud_sharee.dart';
 import '../providers/server_provider.dart';
+import 'details/details_sheet.dart' show DetailsHeader;
 import 'gradual_bottom_sheet.dart';
 
 IconData _shareTypeIcon(ShareType type) {
@@ -217,12 +218,15 @@ class _ShareSheetState extends State<ShareSheet> {
   }
 
   Widget _sectionHeader(String label) {
-    final colorScheme = Theme.of(context).colorScheme;
+    final theme = Theme.of(context);
+    final colorScheme = theme.colorScheme;
     return Row(
       children: [
         Text(
           label,
-          style: const TextStyle(fontWeight: FontWeight.w700, fontSize: 15),
+          style: theme.textTheme.titleSmall?.copyWith(
+            fontWeight: FontWeight.w700,
+          ),
         ),
         const SizedBox(width: 6),
         Icon(
@@ -301,17 +305,16 @@ class _ShareSheetState extends State<ShareSheet> {
 
     return ListView(
       controller: widget.scrollController,
-      padding: const EdgeInsets.fromLTRB(20, 12, 20, 24),
+      padding: const EdgeInsets.fromLTRB(20, 0, 20, 24),
       children: [
-        Text(
-          widget.item.name,
-          maxLines: 1,
-          overflow: TextOverflow.ellipsis,
-          style: theme.textTheme.titleMedium?.copyWith(
-            fontWeight: FontWeight.w700,
-          ),
+        // Same icon/name/meta header as DetailsSheet, so this and its
+        // sibling per-item bottom sheet open on identical chrome - just a
+        // bare title `Text` here read as under-designed by comparison.
+        DetailsHeader(
+          item: widget.item,
+          padding: const EdgeInsets.only(top: 12, bottom: 8),
         ),
-        const SizedBox(height: 16),
+        const SizedBox(height: 8),
         _sectionHeader('Internal shares'),
         const SizedBox(height: 8),
         TextField(
@@ -380,7 +383,7 @@ class _ShareSheetState extends State<ShareSheet> {
           keyboardType: TextInputType.emailAddress,
           decoration: InputDecoration(
             hintText: 'Type an email',
-            prefixIcon: const Icon(Icons.email_outlined),
+            prefixIcon: const Icon(Icons.email_rounded),
             border: OutlineInputBorder(borderRadius: BorderRadius.circular(16)),
             filled: true,
             fillColor: colorScheme.surfaceContainerLow,

lib/widgets/synced_header_scaffold.dart

@@ -41,6 +41,15 @@ class SyncedHeaderScaffold extends StatefulWidget {
   /// `provider.fetchTrash` for a tab backed by different data.
   final Future<void> Function()? onRefresh;
 
+  /// When non-null (a tab is mid-selection), this takes over the pinned top
+  /// bar entirely - replacing the sync-status chip, [actions], and the
+  /// pull-to-reveal quota panel - instead of appearing as a second app bar
+  /// further down in [contentSlivers]. Selection is a modal-ish state (you
+  /// came here to act on specific items), so it reads better as the one
+  /// thing at the very top than as a strip sandwiched under the normal
+  /// chrome.
+  final Widget? selectionBar;
+
   const SyncedHeaderScaffold({
     super.key,
     required this.scrollController,
@@ -48,6 +57,7 @@ class SyncedHeaderScaffold extends StatefulWidget {
     required this.actions,
     required this.contentSlivers,
     this.onRefresh,
+    this.selectionBar,
   });
 
   @override
@@ -175,22 +185,32 @@ class _SyncedHeaderScaffoldState extends State<SyncedHeaderScaffold> {
               slivers: [
                 SliverAppBar(
                   pinned: true,
-                  stretch: true,
-                  expandedHeight: _headerLocked ? 190 : kToolbarHeight,
+                  stretch: widget.selectionBar == null,
+                  expandedHeight: widget.selectionBar != null
+                      ? kToolbarHeight
+                      : (_headerLocked ? 190 : kToolbarHeight),
                   collapsedHeight: kToolbarHeight,
                   backgroundColor: colorScheme.surfaceContainer,
                   surfaceTintColor: colorScheme.surfaceContainer,
                   scrolledUnderElevation: 0,
                   automaticallyImplyLeading: false,
-                  leadingWidth: _headerLocked ? 56 : 160,
-                  leading: leadingWidget,
-                  actions: widget.actions,
-                  flexibleSpace: FlexibleSpaceBar(
-                    background: _SyncedStretchPanel(
-                      provider: provider,
-                      forceVisible: _headerLocked,
-                    ),
-                  ),
+                  leadingWidth: widget.selectionBar != null
+                      ? 0
+                      : (_headerLocked ? 56 : 160),
+                  leading: widget.selectionBar != null ? null : leadingWidget,
+                  titleSpacing: widget.selectionBar != null ? 0 : null,
+                  title: widget.selectionBar,
+                  actions: widget.selectionBar != null
+                      ? const []
+                      : widget.actions,
+                  flexibleSpace: widget.selectionBar != null
+                      ? null
+                      : FlexibleSpaceBar(
+                          background: _SyncedStretchPanel(
+                            provider: provider,
+                            forceVisible: _headerLocked,
+                          ),
+                        ),
                 ),
                 DecoratedSliver(
                   decoration: BoxDecoration(