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/viewer_icon_button.dart

@@ -1,22 +1,22 @@
 import 'package:flutter/material.dart';
+import '../../theme/design_tokens.dart';
 
 /// Icon-only action button for the media viewer's floating chrome (top bar,
 /// bottom action bar, video transport controls) - a fixed 22px icon in a
-/// round hit box. Colored white by default, not from [NooColors]/
-/// [ColorScheme]: this chrome always sits on the dark translucent panel
-/// over a black media stage (see `FrostedGlassContainer`'s doc comment),
-/// regardless of the app's light/dark theme, so a theme-derived color would
-/// go near-invisible in light mode. Kept as one small widget so every
-/// floating control in this screen looks the same instead of drifting
-/// apart across the three call sites that need one.
+/// round hit box. Colored from [NooColors.fg1] by default, matching
+/// [FrostedGlassContainer]'s own theme-following panel underneath it (both
+/// used to be fixed white-on-black regardless of theme - see their git
+/// history). Kept as one small widget so every floating control in this
+/// screen looks the same instead of drifting apart across the three call
+/// sites that need one.
 class ViewerIconButton extends StatelessWidget {
   final IconData icon;
   final String tooltip;
   final VoidCallback? onTap;
 
-  /// Overrides the default white (e.g. `danger` for delete, `accent-text`
-  /// for a favorited state). Ignored while [onTap] is null - a disabled
-  /// button always dims to faded white regardless of its normal color.
+  /// Overrides the default [NooColors.fg1] (e.g. `danger` for delete,
+  /// `accent-text` for a favorited state). Ignored while [onTap] is null -
+  /// a disabled button always dims regardless of its normal color.
   final Color? color;
 
   const ViewerIconButton({
@@ -29,9 +29,8 @@ class ViewerIconButton extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    final fg = onTap == null
-        ? Colors.white.withValues(alpha: 0.4)
-        : (color ?? Colors.white);
+    final fg1 = context.nooColors.fg1;
+    final fg = onTap == null ? fg1.withValues(alpha: 0.4) : (color ?? fg1);
 
     return Tooltip(
       message: tooltip,