feat(desktop): Linux AppImage releases and desktop feature parity (#2398)

* feat(electron): add Linux AppImage releases

* ci: cache Linux OpenCode CLI artifacts

* fix(ci): await Linux release inventory check

* fix(electron): add frameless window controls on Linux desktop

Linux AppImages were created without native WM decorations and without
in-app controls, leaving users unable to close the window with a mouse.

Treat Linux like Windows: frameless BrowserWindow plus the existing
WindowsWindowControls header buttons and app-menu entry. macOS keeps
hidden title bar with traffic lights unchanged.

Shared usesFramelessElectronChrome() helper drives main window, mini
chat, header insets, and titlebar controls.

Co-authored-by: Serhii Dziupin <makeittech@users.noreply.github.com>

* Linux desktop feature parity: Open in, background start, tray, multi-window (#2392)

* feat(electron): Linux parity for Open in, background start, and tray

Enable Linux desktop feature parity with macOS/Windows: open projects in
the default file manager and discovered apps, XDG autostart with
--background launches, system tray (including minimize-to-tray), and
tray sync from the renderer.

Co-authored-by: Serhii Dziupin <makeittech@users.noreply.github.com>

* fix(electron): allow packaged UI protocol navigations on Linux

Prevent openchamber-ui:// navigations from being handed to
shell.openExternal, which fails on Linux and blocked desktop UI flows.

Co-authored-by: Serhii Dziupin <makeittech@users.noreply.github.com>

* fix(ui): surface Linux tray settings in settings search

Include isLinux in settings search runtime context so minimize-to-tray
is discoverable on Linux desktop, matching Windows search behavior.

Co-authored-by: Serhii Dziupin <makeittech@users.noreply.github.com>

* fix(electron): stop Linux AppImage Waiting-for-OpenCode flicker

Sync updated boot-outcome init scripts to all BrowserWindows after
desktop_hosts_set, and prefer state.initScript on dom-ready so chooser
reloads inject local/ok instead of a stale not-configured outcome.

Co-authored-by: Serhii Dziupin <makeittech@users.noreply.github.com>

---------

Co-authored-by: Cursor Agent <cursoragent@cursor.com>
Co-authored-by: Serhii Dziupin <makeittech@users.noreply.github.com>

* fix(desktop): restore Linux AppImage updater feed and error UX (#2396)

Treat missing latest-linux*.yml (404) as no update available instead of a
hard failure, and stop swallowing updater capability/download errors in the
desktop bridge so About/sidebar can show actionable messages.

Co-authored-by: Cursor Agent <cursoragent@cursor.com>
Co-authored-by: Serhii Dziupin <makeittech@users.noreply.github.com>

* docs: credit Linux AppImage contributors in changelog

Co-authored-by: Serhii Dziupin <makeittech@users.noreply.github.com>

---------

Co-authored-by: jibanez-staticduo <staticduo@gmail.com>
Co-authored-by: Serhii Dziupin <makeittech@users.noreply.github.com>

packages/ui/src/lib/openInApps.ts

@@ -35,10 +35,18 @@ export const DEFAULT_OPEN_IN_APP_ID = 'finder';
 export const OPEN_IN_ALWAYS_AVAILABLE_APP_IDS = new Set(['finder', 'terminal']);
 
 export const getPlatformOpenInApp = (app: OpenInApp): OpenInApp => {
-  if (typeof window !== 'undefined' && window.__OPENCHAMBER_PLATFORM__ === 'win32') {
-    if (app.id === 'finder') {
+  if (typeof window === 'undefined') {
+    return app;
+  }
+
+  const platform = window.__OPENCHAMBER_PLATFORM__;
+  if (app.id === 'finder') {
+    if (platform === 'win32') {
       return { ...app, label: 'Explorer', appName: 'File Explorer' };
     }
+    if (platform === 'linux') {
+      return { ...app, label: 'File Manager' };
+    }
   }
   return app;
 };