feat: P1 features — quick switcher, media gallery, DM previews, knock-to-join, syntax highlighting

P1-1: Quick room switcher (Ctrl+K/Cmd+K) — QuickSwitcher.tsx + ClientNonUIFeatures hotkey
P1-2: Media gallery drawer (images/videos/files) — MediaGallery.tsx + RoomViewHeader toggle
P1-4: DM last message preview + relative timestamp in RoomNavItem when direct=true
P1-7: Code syntax highlighting — TDS tokenizer (syntaxHighlight.ts), custom CSS theme
       (.prism-tds-dark/.prism-tds-light), applied in react-custom-html-parser.tsx
P1-11: Knock-to-join — "Request to Join" in RoomIntro + Pending Requests in MembersDrawer

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/app/hooks/useTheme.ts

@@ -46,7 +46,7 @@ export const ButterTheme: Theme = {
 export const LotusTerminalTheme: Theme = {
   id: 'lotus-terminal-theme',
   kind: ThemeKind.Dark,
-  classNames: ['lotus-terminal-theme', lotusTerminalTheme, onDarkFontWeight, 'prism-dark'],
+  classNames: ['lotus-terminal-theme', lotusTerminalTheme, onDarkFontWeight, 'prism-tds-dark'],
 };
 export const LotusTerminalLightTheme: Theme = {
   id: 'lotus-terminal-light-theme',
@@ -55,7 +55,7 @@ export const LotusTerminalLightTheme: Theme = {
     'lotus-terminal-light-theme',
     lotusTerminalLightTheme,
     onLightFontWeight,
-    'prism-light',
+    'prism-tds-light',
   ],
 };