fix: explicitly clear storage for new account logins to prevent session leakage

frontend/electron/main.ts

@@ -528,6 +528,12 @@ ipcMain.handle('open-steam-login', async (event, expectedSteamId: string) => {
   const partitionId = expectedSteamId ? `persist:steam-login-${expectedSteamId}` : 'persist:steam-login-new';
   const loginSession = session.fromPartition(partitionId);
 
+  // If adding a brand new account, explicitly clear previous trash
+  if (!expectedSteamId) {
+    console.log('[Auth] Clearing session for new account login...');
+    await loginSession.clearStorageData({ storages: ['cookies', 'localstorage', 'indexdb'] });
+  }
+
   // If we have an existing cookie string for this account, pre-inject it
   if (expectedSteamId) {
     const accounts = store.get('accounts') as Account[];