Show BanGUI app version in sidebar, fix version tooltips

- Inject __APP_VERSION__ at build time via vite.config.ts define (reads
  frontend/package.json#version); declare the global in vite-env.d.ts.
- Render 'BanGUI v{__APP_VERSION__}' in the sidebar footer (MainLayout)
  when expanded; hidden when collapsed.
- Rename fail2ban version tooltip to 'fail2ban daemon version' in
  ServerStatusBar so it is visually distinct from the app version.
- Sync frontend/package.json version (0.9.0 → 0.9.3) to match
  Docker/VERSION; update release.sh to keep them in sync on every bump.
- Add vitest define stub for __APP_VERSION__ so tests compile cleanly.
- Add ServerStatusBar and MainLayout test suites (10 new test cases).

frontend/src/vite-env.d.ts

@@ -7,3 +7,6 @@ interface ImportMetaEnv {
 interface ImportMeta {
   readonly env: ImportMetaEnv;
 }
+
+/** BanGUI application version — injected at build time via Vite define. */
+declare const __APP_VERSION__: string;