[Bug] readConfig silently returns null on parse errors, losing user config

Problem

readConfig wraps the whole read/parse/decrypt pipeline in a bare catch {} that returns null on any error. If the config file is corrupted (partial write, disk error, bad manual edit), the user sees a completely empty app — all gateway configurations, language settings, and preferences silently disappear. No error is logged and no backup is kept, so recovery is impossible.

Location

File: packages/desktop/src/main/workspace/config.ts:155-166

export function readConfig(): AppConfig | null {
  const cfgPath = configFilePath();
  if (!existsSync(cfgPath)) return null;
  try {
    const raw = readFileSync(cfgPath, 'utf-8');
    const config = JSON.parse(raw) as AppConfig;
    const migrated = migrateConfigIfNeeded(config);
    return decryptGatewayCredentials(migrated);
  } catch {
    return null;
  }
}

Fix Approach

1. In the catch block, log the error via console.error('[config] failed to read:', err).
2. Rename the corrupted file to config.json.corrupted-<ISO timestamp> so the user has a recovery artifact on disk.
3. Return null as before, so the first-run flow still kicks in.

Verification

1. Run pnpm check — must pass.
2. Manual: write garbage into the config file, launch the app, check that:
   • The corrupted file is renamed with a .corrupted-* suffix.
   • The main process log contains the error.
   • The app still launches into the first-run flow.

Context

• WG: Artifact & File System
• Priority: Low (good first issue)
• Estimated effort: 20-30 minutes