- Add federation.config.ts with UUID v4 validation for DEFAULT_WORKSPACE_ID - Validate at module initialization (fail fast if misconfigured) - Replace hardcoded "default" fallback with proper validation - Add 18 tests covering valid UUIDs, invalid formats, and missing values - Clear error messages with expected UUID format Refs #338 Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>