Replace String() calls with .toString()/.toLocaleString() per ast-grep rule

- Add formatError() helper in CLI to safely handle unknown error types
- Add uniqueTestId() helper for generating unique test identifiers
- Replace String(id) with id.toString() for database ID conversions
- Replace String(n) with n.toLocaleString() for user-facing number formatting
- Fix TypeScript errors in test files (undefined checks, unused variables)
- Update lint commands to include ast-grep scanning

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

apps/api-server/src/router.ts

@@ -139,7 +139,7 @@ const verifyAuthentication = os.auth.webauthn.verifyAuthentication
     await context.db
       .updateTable("login_requests")
       .set({ completed_at: new Date() })
-      .where("id", "=", String(context.loginRequestId))
+      .where("id", "=", context.loginRequestId.toString())
       .execute();
 
     return { success: true };