feat: Implement Electron window state persistence, update checking with splash screen and banner, and external link metadata fetching.

Frontend/Electron/preload.cjs

@@ -32,6 +32,10 @@ contextBridge.exposeInMainWorld('appSettings', {
     set: (key, value) => ipcRenderer.invoke('set-setting', key, value),
 });
 
+contextBridge.exposeInMainWorld('updateAPI', {
+    checkFlatpakUpdate: () => ipcRenderer.invoke('check-flatpak-update'),
+});
+
 contextBridge.exposeInMainWorld('sessionPersistence', {
     save: (data) => ipcRenderer.invoke('save-session', data),
     load: () => ipcRenderer.invoke('load-session'),