feat: add Quick Prompt global hotkey popup for one-off AI questions

Add a system-wide global hotkey (Win+Shift+A / Cmd+Shift+A) that summons
a floating, frameless popup window for quick AI interactions from any app.

Main process:
- GlobalHotkeyService for registering/unregistering system-wide shortcuts
- Frameless, transparent, always-on-top BrowserWindow factory
- IPC handlers for send, discard, close, continue-in-aryx, cancel
- Session event routing from sidecar to quick prompt window
- Settings persistence for default model, hotkey, and reasoning effort

Renderer (separate lightweight entry):
- QuickPromptApp with session state, streaming, keyboard shortcuts
- QuickPromptInput with model selector trigger and cancel support
- QuickPromptResponse with streamed markdown and thinking blocks
- QuickPromptActions (Discard / Close / Continue in Aryx)
- ModelSelector dropdown with tier badges and reasoning effort
- Glass Command Bar aesthetic with animated gradient border

Settings:
- Quick Prompt section in SettingsPanel with enable toggle, hotkey
  display, default model selector, and reasoning effort picker

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

src/preload/index.ts

@@ -36,6 +36,8 @@ const api: ElectronApi = {
   setNotificationsEnabled: (enabled) => ipcRenderer.invoke(ipcChannels.setNotificationsEnabled, enabled),
   setMinimizeToTray: (enabled) => ipcRenderer.invoke(ipcChannels.setMinimizeToTray, enabled),
   setGitAutoRefreshEnabled: (enabled) => ipcRenderer.invoke(ipcChannels.setGitAutoRefreshEnabled, enabled),
+  getQuickPromptSettings: () => ipcRenderer.invoke(ipcChannels.quickPromptGetSettings),
+  setQuickPromptSettings: (settings) => ipcRenderer.invoke(ipcChannels.quickPromptSetSettings, settings),
   checkForUpdates: () => ipcRenderer.invoke(ipcChannels.checkForUpdates),
   installUpdate: () => ipcRenderer.invoke(ipcChannels.installUpdate),
   saveMcpServer: (input) => ipcRenderer.invoke(ipcChannels.saveMcpServer, input),