fix(ui): avatar-decoration reliability, Saved Messages + Media Gallery redesign

Avatar decorations: useAvatarDecoration cached ALL profile-field fetch
failures as "no decoration" permanently for the session. The member list
and timeline mount many avatars at once, so one rate-limited (429) burst
would wipe everyone's decoration until a full reload. Now only a genuine
404 (field unset) is cached; transient errors retry on the next mount.

Saved Messages panel — full redesign to match the canonical MembersDrawer:
- co-located BookmarksPanel.css.ts: toRem(266) + max-width:750px full-screen
  media query, replacing the old position:absolute/zIndex:100 mobile "modal"
  that had no backdrop or escape
- variant="Background" header; room avatars on each item (was a generic hash)
- priority tokens replace all raw opacity hacks; 3px borderLeft accent removed
- Escape-to-close; multi-line preview is now a proper folds Button (N38)

Media Gallery (N12): moved fixed positioning + width into MediaGallery.css.ts
using toRem(320) + a full-screen media query; border/header use config tokens;
added Escape-to-close on the panel (previously only the lightbox handled it).

Presence (SettingsTab / useUserPresence):
- N16: wrap presence-dot trigger in TooltipProvider; replace undefined
  --bg-surface with color.Background.Container
- N17: add escapeDeactivates + isKeyForward/isKeyBackward to the FocusTrap
- N19: align reader labels (usePresenceLabel) to the setter vocabulary
  (Online/Idle/Offline) so a chosen status matches the tooltip others see

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app/features/bookmarks/BookmarksPanel.css.ts

@@ -0,0 +1,42 @@
+import { style } from '@vanilla-extract/css';
+import { config, toRem } from 'folds';
+
+// Mirrors MembersDrawer: a 266px side panel on desktop that becomes a
+// full-screen fixed panel on narrow viewports — the app's canonical drawer.
+export const BookmarksPanel = style({
+  width: toRem(266),
+  '@media': {
+    '(max-width: 750px)': {
+      position: 'fixed',
+      inset: 0,
+      width: '100%',
+      zIndex: 500,
+    },
+  },
+});
+
+export const BookmarksHeader = style({
+  flexShrink: 0,
+  padding: `0 ${config.space.S200} 0 ${config.space.S300}`,
+  borderBottomWidth: config.borderWidth.B300,
+});
+
+export const BookmarksToolbar = style({
+  flexShrink: 0,
+  padding: config.space.S200,
+  borderBottomWidth: config.borderWidth.B300,
+});
+
+export const BookmarksContent = style({
+  padding: config.space.S200,
+});
+
+export const BookmarkPreview = style({
+  width: '100%',
+  display: '-webkit-box',
+  WebkitLineClamp: 2,
+  WebkitBoxOrient: 'vertical',
+  overflow: 'hidden',
+  wordBreak: 'break-word',
+  textAlign: 'left',
+});