Fix terminal UI regressions, font fallback handling, and hook session routing

[oso95]

• fix terminal font selection and platform fallback handling

  • use platform-specific default terminal fonts instead of JetBrains Mono everywhere
  • sanitize saved terminal fonts against detected installed monospace fonts
  • fall back to an installed platform-appropriate font on Windows/macOS instead of keeping stale missing fonts in settings
  • stop showing unavailable terminal fonts in the settings dropdown

• add terminal search and keyboard shortcut support

  • add Cmd/Ctrl+F terminal search action and keybinding wiring
  • add literal case-insensitive terminal search over the Alacritty grid
  • render match highlights in the terminal viewport
  • support next/previous match navigation
  • add search markers to the terminal scrollbar

• fix terminal search input and keyboard navigation

  • stop swallowing printable input before GPUI text insertion reaches the search field
  • allow typing into the search box again
  • add keyboard focus state for search controls
  • support Tab / Shift+Tab navigation across input, prev, next, and close
  • support Enter / Space activation for focused search controls

• add terminal scrollbar interactions

  • render terminal scrollbars with hover/fade behavior
  • support track clicking and thumb dragging
  • keep scrollbar visibility in sync with scroll activity

• fix shortcut recording focus in settings

  • restore workspace focus when clicking a shortcut row so the next shortcut is actually captured
  • update the recording prompt to say Press a shortcut... to match the supported behavior

• fix layout toggle to follow saved/top-bar profiles

  • switch toggle layout from the legacy hardcoded LayoutProfile cycle to the top bar/profile manager sequence
  • keep active layout state synced with saved/custom layout profiles
  • clear invalid active-profile state instead of leaving stale selection behind
  • prevent shortcut-driven layout cycling from surfacing layouts that are not in the current visible profile set

• fix task board shortcut conflict

  • keep sidebar on Cmd/Ctrl+B
  • move task board toggle to Cmd/Ctrl+T
  • avoid the previous Cmd/Ctrl+B overlap

• fix hook signal routing by stable UUID/session identity

  • prefer CLI-provided session IDs and Codirigent session UUIDs over the legacy integer session ID path
  • route Codex/Gemini hook signals by UUID when available
  • avoid backfilling CLI session IDs from filenames when the filename is actually the Codirigent session UUID
  • keep Claude routing behavior consistent while tightening fallback behavior

Verification

• cargo fmt --all
• cargo check -p codirigent-ui --features gpui-full
• targeted codirigent-ui tests for terminal search, layout profile cycling, and top bar active-profile clearing
• prior branch verification also covered full build/test/clippy gates and unwrap audit