Rebuild UI on the Noo design system

Replaces the Material 3 screens with the Noo design system: warm
neutrals, one violet accent, pill controls, Schibsted Grotesk/
Instrument Sans, Lucide icons, no gradients/shadows.

- New lib/widgets/noo/ component kit (core, lists, files, media, nav,
  overlays) plus lib/theme/design_tokens.dart for the color/type/space/
  radius/motion tokens.
- Rebuilt the app shell (top/bottom bars, drawer, desktop sidebar and
  toolbar), every tab (Files/Offline, Photos, Favorites, Recent,
  Activity, Trash, Shares), Settings, the lock and login screens, the
  media viewer, search, the details/share sheets, and the share-upload
  and move/copy destination pickers.
- Added a design canvas (linked from DESIGN_SYSTEM.md) covering the
  screens the spec didn't already describe, with matching Android and
  iOS chrome; wrote up the approved recipes into DESIGN_SYSTEM.md §4.
- Removed now-dead legacy widgets (media_grid_tile, swipeable_item,
  sync_status_badge, selectable_thumbnail) and updated
  architecture.md/styling.md/standards.md to describe the new
  structure and component/testing conventions.
- Added widget tests for the noo/ component kit.

This is a UI-only rework: no provider/model/service behavior changed.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

lib/widgets/breadcrumbs.dart

@@ -1,7 +1,13 @@
 import 'package:flutter/material.dart';
+import 'package:lucide_icons_flutter/lucide_icons.dart';
+import '../theme/design_tokens.dart';
 
 /// Tappable "Home / Folder / Sub-folder" trail shown whenever the user has
-/// navigated below the root, in both the Files and Photos tabs.
+/// navigated below the root - now only used by `ShareUploadView` and
+/// `MoveCopyDestinationPicker` (Files/Photos moved to their own noo-styled
+/// `FileBreadcrumbRow`), so this is free to carry noo tokens directly rather
+/// than staying on the old Material look. Same behaviour: every crumb but
+/// the last is tappable, jumping back to that depth.
 class Breadcrumbs extends StatelessWidget {
   final List<String> pathStack;
   final ValueChanged<int> onTap;
@@ -19,8 +25,7 @@ class Breadcrumbs extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    final theme = Theme.of(context);
-    final colorScheme = theme.colorScheme;
+    final colors = context.nooColors;
     final lastIndex = pathStack.length - 1;
 
     return SingleChildScrollView(
@@ -32,37 +37,42 @@ class Breadcrumbs extends StatelessWidget {
               Padding(
                 padding: const EdgeInsets.symmetric(horizontal: 2),
                 child: Icon(
-                  Icons.chevron_right_rounded,
-                  size: 16,
-                  color: colorScheme.outlineVariant,
+                  LucideIcons.chevronRight,
+                  size: 14,
+                  color: colors.fg3,
                 ),
               ),
             if (i == lastIndex)
               Padding(
-                padding: const EdgeInsets.symmetric(horizontal: 8),
+                padding: const EdgeInsets.symmetric(horizontal: 6),
                 child: Text(
                   _labelFor(i),
-                  style: theme.textTheme.bodySmall?.copyWith(
-                    fontWeight: FontWeight.w700,
-                    color: colorScheme.onSurface,
+                  style: NooText.body.copyWith(
+                    fontSize: 13,
+                    fontWeight: FontWeight.w600,
+                    color: colors.fg1,
                   ),
                 ),
               )
             else
-              // A chip's whole pill is the tap target (not just the text),
-              // so the previous plain-text crumbs were fiddly to hit.
-              ActionChip(
-                label: Text(_labelFor(i)),
-                labelStyle: theme.textTheme.bodySmall?.copyWith(
-                  fontWeight: FontWeight.w600,
-                  color: colorScheme.primary,
+              // The whole pill is the tap target, not just the text.
+              InkWell(
+                onTap: () => onTap(i),
+                borderRadius: BorderRadius.circular(NooRadii.pill),
+                child: Padding(
+                  padding: const EdgeInsets.symmetric(
+                    horizontal: 8,
+                    vertical: 4,
+                  ),
+                  child: Text(
+                    _labelFor(i),
+                    style: NooText.body.copyWith(
+                      fontSize: 13,
+                      fontWeight: FontWeight.w600,
+                      color: colors.accentText,
+                    ),
+                  ),
                 ),
-                onPressed: () => onTap(i),
-                backgroundColor: colorScheme.surfaceContainerHigh,
-                side: BorderSide.none,
-                visualDensity: VisualDensity.compact,
-                materialTapTargetSize: MaterialTapTargetSize.shrinkWrap,
-                padding: const EdgeInsets.symmetric(horizontal: 4),
               ),
           ],
         ],