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/frosted_glass_container.dart

@@ -1,15 +1,18 @@
 import 'dart:ui';
 import 'package:flutter/material.dart';
+import '../theme/design_tokens.dart';
 
 /// The blurred/translucent chrome for the media viewer's overlay bars
 /// (`file_viewer_screen.dart`'s top bar, `MediaActionBar`, the video
 /// transport row) - the one deliberate exception to the design system's
 /// flat, no-shadow product UI (DESIGN_SYSTEM.md 1.4), since this chrome
 /// floats over photo/video content rather than over the app's own
-/// surfaces. No shadow, no outline, no `ColorScheme` tint: a fixed dark
-/// translucent fill (`color`) that reads correctly over any media,
-/// regardless of the app's light/dark theme - matching the canvas at
-/// https://claude.ai/artifact/3AGPqqMdkLSC2ypCh2CQs4.
+/// surfaces. No shadow, no outline: [color] defaults to the app's own
+/// `surface` token (so this panel reads as light or dark to match the
+/// active theme, like the rest of the media viewer, instead of a fixed
+/// dark tone regardless of theme) at a higher-than-usual [opacity], since
+/// a light tint needs denser coverage than a near-black one did to stay
+/// legible over arbitrary photo/video brightness underneath.
 class FrostedGlassContainer extends StatelessWidget {
   final Widget child;
   final double borderRadius;
@@ -23,30 +26,30 @@ class FrostedGlassContainer extends StatelessWidget {
   /// adjustable.
   final double opacity;
 
-  /// The tint under the blur. Defaults to the design's fixed dark tone
-  /// (`#141311`, the spec's `fg-1` dark value) - deliberately not a
-  /// `ColorScheme`/`NooColors` lookup, since this chrome always sits over a
-  /// black media stage, not over a themed surface.
-  final Color color;
+  /// The tint under the blur. Defaults to [NooColors.surface] (resolved at
+  /// build time, so it always matches the active theme) - pass an explicit
+  /// color only to override that, e.g. for a fixed-color panel elsewhere.
+  final Color? color;
 
   const FrostedGlassContainer({
     super.key,
     required this.child,
     this.borderRadius = 0,
     this.blurSigma = 20,
-    this.opacity = 0.55,
-    this.color = const Color(0xFF141311),
+    this.opacity = 0.8,
+    this.color,
   });
 
   @override
   Widget build(BuildContext context) {
+    final tint = color ?? context.nooColors.surface;
     return ClipRRect(
       borderRadius: BorderRadius.circular(borderRadius),
       child: BackdropFilter(
         filter: ImageFilter.blur(sigmaX: blurSigma, sigmaY: blurSigma),
         child: Container(
           decoration: BoxDecoration(
-            color: color.withValues(alpha: opacity),
+            color: tint.withValues(alpha: opacity),
             borderRadius: BorderRadius.circular(borderRadius),
           ),
           child: child,