fix: ensure fresh Steam login on Add by killing process and clearing auto-login state

frontend/electron/main.ts

@@ -506,9 +506,18 @@ ipcMain.handle('switch-account', async (event, loginName: string) => await handl
 ipcMain.handle('open-external', (event, url: string) => shell.openExternal(url));
 
 ipcMain.handle('open-steam-app-login', async () => {
-  console.log('[SteamClient] Triggering desktop login window...');
-  // Force Steam to show login window. 
-  // steam://open/login is the protocol for this.
+  console.log('[SteamClient] Preparing for fresh login...');
+  await killSteam();
+
+  if (process.platform === 'win32') {
+    // Clear auto-login registry
+    const clearReg = 'reg add "HKCU\\Software\\Valve\\Steam" /v AutoLoginUser /t REG_SZ /d "" /f';
+    await new Promise<void>((res) => exec(clearReg, () => res()));
+  } else if (process.platform === 'linux') {
+    // On Linux we can use the steamClient helper to set an empty user
+    await steamClient.setAutoLoginUser("", undefined, "");
+  }
+
   const command = process.platform === 'win32' ? 'start steam://open/login' : 'xdg-open steam://open/login';
   exec(command);
   return true;