Fix sheet peek for async content, and rework several screens' details

showNooSheet's peek detection previously measured content once, right
after the first frame - Details' Versions/Activity tabs fetch their
data asynchronously, so that one-shot measurement only ever saw the
initial loading-spinner height, never the eventual (often long) list,
and the sheet still snapped to full height once data arrived. Replaced
it with a ScrollMetricsNotification-based check that keeps content
capped at the peek height from frame one and upgrades to a draggable
sheet whenever it actually overflows that cap, however and whenever
that happens - fixed for good this time, with a regression test that
mirrors the async-load shape.

Also, in the same pass:
- Upload/Move/Copy's bottom bar meta line now always reads as a count
  ("Uploading 3 items"), never a filename for the single-item case,
  and is centered rather than left-aligned - matches the approved
  design and removes a bespoke marquee/chip implementation that only
  Upload had.
- Upload/Move/Copy now show the same FilesControlsRow (sort, filter,
  List/Grid) Files itself uses, including a folder-grid rendering
  path for when List/Grid is set to grid.
- Files' filter chip reads "Filters" instead of "All types" when idle.
- Trash's overflow button - whose only action is "Delete forever" -
  is now a direct delete icon (mobile) / "Delete" danger pill
  (desktop) instead of a generic "..." menu that hid a single action
  behind an extra tap.
- The media viewer's floating chrome (top bar, bottom action bar,
  video transport row) now follows the app's light/dark theme instead
  of a fixed dark panel - a dark panel read as out of place over a
  light-theme stage. Panel tint and icon/text colors come from the
  theme's own surface/fg1 tokens (at a higher blur opacity to stay
  legible over arbitrary photo/video brightness), and the edge scrim
  gradients fade toward the panel's own tint instead of a fixed black.
  Mirrored the same change into the design canvas's Main.dc.html/
  MainAndroid.dc.html mockups (now with a theme prop) so they match.

lib/widgets/viewer/media_action_bar.dart

@@ -40,11 +40,7 @@ class MediaActionBar extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    // This panel always sits on a black media stage regardless of the
-    // app's own light/dark theme (see FrostedGlassContainer's doc
-    // comment) - fixed dark-palette values, not `context.nooColors`, so
-    // favorite/delete stay legible even when the ambient theme is light.
-    const dark = NooColors.dark;
+    final colors = context.nooColors;
 
     // The blurred/tinted background lives outside the SafeArea (not inside
     // it) so it extends all the way to the physical bottom edge, behind the
@@ -59,7 +55,7 @@ class MediaActionBar extends StatelessWidget {
           children: [
             if (transportControls != null) ...[
               transportControls!,
-              Divider(height: 1, color: Colors.white.withValues(alpha: 0.14)),
+              Divider(height: 1, color: colors.fg1.withValues(alpha: 0.14)),
             ],
             Padding(
               padding: const EdgeInsets.symmetric(horizontal: 6, vertical: 6),
@@ -80,7 +76,7 @@ class MediaActionBar extends StatelessWidget {
                       tooltip: isFavorite
                           ? 'Remove from favorites'
                           : 'Favorite',
-                      color: isFavorite ? dark.accentText : null,
+                      color: isFavorite ? colors.accentText : null,
                       onTap: onFavorite,
                     ),
                   ViewerIconButton(
@@ -98,7 +94,7 @@ class MediaActionBar extends StatelessWidget {
                     ViewerIconButton(
                       icon: LucideIcons.trash2,
                       tooltip: 'Delete',
-                      color: dark.danger,
+                      color: colors.danger,
                       onTap: isBusy ? null : onDelete,
                     ),
                   ViewerIconButton(