Show app version in sidebar, make the sidebar collapsible, and add a Light/Dark/Auto theme switch

- Expose the AeroFetch version over IPC (app:version → app.getVersion); the
  sidebar brand now shows "v<version>" beneath the name.
- Sidebar can collapse to a 60px icon-only rail via a toggle button; nav items
  and the theme control fall back to icon + tooltip when collapsed. The state is
  persisted in localStorage so it survives restarts. Hint gains left/right
  placements for the collapsed-rail tooltips.
- Replace the binary dark-mode Switch with an explicit 3-way Light / Dark / Auto
  segmented control (Auto follows the OS). Collapsed, it becomes a single button
  that cycles the three modes.
- Bump version to 0.3.2.

Verified in the browser UI preview: version label, collapse/expand, dark mode,
and the theme switch all render correctly with no console errors.

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

src/main/index.ts

@@ -151,6 +151,8 @@ function createWindow(): void {
 }
 
 function registerIpcHandlers(): void {
+  ipcMain.handle(IpcChannels.appVersion, () => app.getVersion())
+
   ipcMain.handle(IpcChannels.ytdlpVersion, () => getYtdlpVersion())
 
   ipcMain.handle(IpcChannels.probe, (_e, url: string) => probeMedia(url))