fix: resolve desktop entry launch failure and hide Electron menu bar on Linux

- Add --ozone-platform-hint=auto before app.whenReady() so Electron
  auto-detects X11 vs Wayland when launched from a desktop entry where
  the display protocol is not guaranteed (fixes immediate crash on
  Fedora/GNOME Wayland sessions)
- Add autoHideMenuBar: true to BrowserWindow so the default Chromium
  File/Edit/View/Help menu bar is hidden by default (still accessible
  via Alt); removes visible Electron significance from the packaged app
- Add scripts/rpm-after-install.sh and wire it via afterInstall in the
  electron-builder RPM config to chmod 4755 chrome-sandbox, ensuring
  the setuid sandbox works on kernels with restricted user namespaces

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/ui/src/main.ts

@@ -48,6 +48,13 @@ if (isDev) {
   }
 }
 
+// On Linux, auto-detect X11 vs Wayland so the app launches correctly from
+// desktop entries where the display protocol isn't guaranteed to be X11.
+// Must be set before app.whenReady() — has no effect on macOS/Windows.
+if (process.platform === 'linux') {
+  app.commandLine.appendSwitch('ozone-platform-hint', 'auto');
+}
+
 // Register IPC handlers
 registerAllHandlers();