Add Trash/Shares/Recent tabs, file sharing, Details sheet, and rebrand to Noo

Major additions since the initial rebuild:
- New tabs: Trash, Shares, Recent, configurable tab visibility/order/default
- Nextcloud sharing: search users/teams, internal link, email shares,
  public links, "others with access" - in its own Share bottom sheet
- Details bottom sheet (Info/Versions/Activity) with a persistent peek
  panel in the media viewer, reachable from selection, swipe, and the
  media viewer
- Files/Photos: tap-and-hold multi-select with a sticky selection toolbar,
  swipe actions (favorite/delete/share), sticky sort/filter controls,
  list/grid views, breadcrumb chips, whole-account Photos view
- Media viewer: pinch/double-tap zoom on images, predictive-back support,
  fixed PDF zoom-out floor
- Settings: Material You theming incl. AMOLED black, configurable bottom
  bar tabs, swipe actions, media seek bar style, and folder-listing cache
  policy (never/periodic/manual) to cut down on refetching
- Login flow moved to an in-app Chrome Custom Tab with retry-tolerant
  polling
- Replaced ad hoc widgets with native Material 3 equivalents (toggle
  IconButtons, SliverAppBar selection toolbar, SearchBar, drag handles)
- Rebrand: app renamed to Noo throughout, package id -> dev.ayushya.noo,
  new adaptive launcher icon

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

lib/models/app_tab.dart

@@ -0,0 +1,47 @@
+import 'package:flutter/material.dart';
+import 'package:material_symbols_icons/symbols.dart';
+
+/// Every destination the bottom nav bar can show. Order here is only the
+/// fallback default — actual order/visibility/default-tab are user
+/// configurable and persisted in [ServerProvider].
+enum AppTab { files, photos, activity, trash, shares, recent }
+
+/// At most this many tabs may be visible in the bottom nav bar at once —
+/// the rest are reachable through the "more" dropdown instead.
+const int maxVisibleTabs = 5;
+
+extension AppTabInfo on AppTab {
+  String get label {
+    switch (this) {
+      case AppTab.files:
+        return 'Files';
+      case AppTab.photos:
+        return 'Photos';
+      case AppTab.activity:
+        return 'Activity';
+      case AppTab.trash:
+        return 'Trash';
+      case AppTab.shares:
+        return 'Shares';
+      case AppTab.recent:
+        return 'Recent';
+    }
+  }
+
+  IconData get icon {
+    switch (this) {
+      case AppTab.files:
+        return Icons.folder_rounded;
+      case AppTab.photos:
+        return Icons.photo_library_rounded;
+      case AppTab.activity:
+        return Icons.electric_bolt_rounded;
+      case AppTab.trash:
+        return Icons.delete_outline_rounded;
+      case AppTab.shares:
+        return Icons.groups_rounded;
+      case AppTab.recent:
+        return Symbols.search_activity_rounded;
+    }
+  }
+}