…s globally

- Fix compact header not collapsing when re-clicking Terminal tab on mobile
- Move terminalShortcuts to SYNCED_SETTINGS_KEYS so shortcuts configured
  on desktop are available on mobile (and vice versa)

…slot mismatch

- Use hidden <input> instead of div[tabindex=0] for key capture so mobile
  browsers show the virtual keyboard
- Reset _isApplyingRemoteSettings guard on nextTick to prevent ping-pong
  loop when backend broadcasts array/object synced settings back to sender
- Pass shortcut data directly to dialog open() to avoid stale prop from
  same-tick reactivity delay
- Dialog now closes itself after save/clear instead of relying on parent
  accessing unexposed template ref

…ab bar

- Backend: SessionContext, tmux window CRUD (create/select/rename/send-keys),
  preset resolution from .twicc-tmux.json, window monitor task, scroll bindings
- Frontend: TmuxNavigator component (shell picker with ad-hoc + preset sections),
  window tab bar (desktop), mobile dropdown, window state management in useTerminal
- Tab re-click cycles: navigator → config (shortcuts) → terminal
- Presets loaded from .twicc-tmux.json with multi-source resolution
  (project dir, git root, session cwd walk)

Move shortcut button slots from separate config panel into the
TmuxNavigator, unifying terminal settings in one place. Unify shell
rendering: all shells use play icon (green when running, grey when not),
presets stay in their source sections in original order.

Allow users to add arbitrary JSON preset files to any project via a file
browser dialog. Preset references are stored in ~/.twicc/presets/<project_id>.json
and loaded as additional sources in the navigator.

- Backend: preset file CRUD (paths.py, terminal.py, views.py), REST API
  endpoint, deduplication against built-in sources, content validation
- Frontend: AddPresetDialog with file tree browser and show-hidden toggle,
  JSON-only file filter, remove button on custom preset sections

Presets can now specify relative_to (preset_dir|project_dir|git_dir|
session_cwd) to control how their cwd is resolved. This enables
library preset files loaded from another directory to run commands
relative to the project root instead of the preset file location.

Presets whose base directory is unavailable are greyed out in the
navigator with a disabled state and explanatory message.

Replace misleading "at the root of your project directory" with the
actual multi-source discovery chain: project dir, git root, then
session cwd walk. Addresses PR review comment about documentation
not reflecting the real lookup behavior.