Add OAuth login support and streamline authentication flows

- Introduced `oauthLogin` method in `electron/preload.ts` and backend IPC handlers for OAuth via `BrowserWindow`.
- Replaced web-based OAuth redirection with Electron-specific implementation for Google, Facebook, and Apple.
- Refactored `SocialForm.tsx` to handle OAuth login success and token management via Electron.
- Updated `User`, `QuillSense`, and context methods to include `quill-trial` subscriptions and extended login logic.
- Cleaned up code, removed unused imports, and improved error handling for authentication scenarios.

electron/main.ts

@@ -188,6 +188,114 @@ ipcMain.handle('open-external', async (_event, url: string) => {
   }
 });
 
+// IPC Handler pour OAuth login via BrowserWindow
+let oauthWindow: BrowserWindow | null = null;
+
+interface OAuthResult {
+  success: boolean;
+  code?: string;
+  state?: string;
+  error?: string;
+}
+
+interface OAuthRequest {
+  provider: 'google' | 'facebook' | 'apple';
+  baseUrl: string;
+}
+
+ipcMain.handle('oauth-login', async (_event, request: OAuthRequest): Promise<OAuthResult> => {
+  return new Promise((resolve) => {
+    const { provider, baseUrl } = request;
+    const redirectUri = `${baseUrl}login?provider=${provider}`;
+    const encodedRedirectUri = encodeURIComponent(redirectUri);
+
+    // Fermer une éventuelle fenêtre OAuth existante
+    if (oauthWindow) {
+      oauthWindow.close();
+      oauthWindow = null;
+    }
+
+    // Configuration OAuth par provider
+    const oauthConfigs: Record<string, string> = {
+      google: `https://accounts.google.com/o/oauth2/v2/auth?client_id=911482317931-pvjog1br22r6l8k1afq0ki94em2fsoen.apps.googleusercontent.com&redirect_uri=${encodedRedirectUri}&response_type=code&scope=openid%20email%20profile&access_type=offline`,
+      facebook: `https://www.facebook.com/v18.0/dialog/oauth?client_id=1015270470233591&redirect_uri=${encodedRedirectUri}&scope=email&response_type=code&state=abc123`,
+      apple: `https://appleid.apple.com/auth/authorize?client_id=eritors.apple.login&redirect_uri=${encodedRedirectUri}&response_type=code&scope=email%20name&response_mode=query&state=abc123`
+    };
+
+    const authUrl = oauthConfigs[provider];
+    if (!authUrl) {
+      resolve({ success: false, error: 'Invalid provider' });
+      return;
+    }
+
+    oauthWindow = new BrowserWindow({
+      width: 600,
+      height: 700,
+      show: true,
+      autoHideMenuBar: true,
+      webPreferences: {
+        nodeIntegration: false,
+        contextIsolation: true,
+      }
+    });
+
+    // Intercepter les redirections pour capturer le code OAuth
+    const handleNavigation = (url: string): boolean => {
+      try {
+        const parsedUrl = new URL(url);
+
+        // Vérifier si c'est notre redirect URI (compare sans le query string)
+        const baseRedirectUri = `${baseUrl}login`;
+        if (url.startsWith(baseRedirectUri)) {
+          const code = parsedUrl.searchParams.get('code');
+          const state = parsedUrl.searchParams.get('state');
+          const error = parsedUrl.searchParams.get('error');
+
+          if (error) {
+            resolve({ success: false, error });
+          } else if (code) {
+            resolve({ success: true, code, state: state || undefined });
+          } else {
+            resolve({ success: false, error: 'No code received' });
+          }
+
+          if (oauthWindow) {
+            oauthWindow.close();
+            oauthWindow = null;
+          }
+          return true; // Navigation interceptée
+        }
+      } catch (e) {
+        // URL invalide, continuer
+      }
+      return false; // Laisser la navigation continuer
+    };
+
+    // Écouter will-redirect (redirections HTTP)
+    oauthWindow.webContents.on('will-redirect', (event, url) => {
+      if (handleNavigation(url)) {
+        event.preventDefault();
+      }
+    });
+
+    // Écouter will-navigate (navigations normales)
+    oauthWindow.webContents.on('will-navigate', (event, url) => {
+      if (handleNavigation(url)) {
+        event.preventDefault();
+      }
+    });
+
+    // Gérer la fermeture de la fenêtre par l'utilisateur
+    oauthWindow.on('closed', () => {
+      oauthWindow = null;
+      resolve({ success: false, error: 'Window closed by user' });
+    });
+
+    // Charger l'URL OAuth
+    oauthWindow.loadURL(authUrl);
+  });
+});
+
 // IPC Handlers pour la gestion du token (OS-encrypted storage)
 ipcMain.handle('get-token', () => {
   const storage:SecureStorage = getSecureStorage();