fix: validate platform keys at the gate and stop auto-register

Co-authored-by: Cursor <cursoragent@cursor.com>

scripts/cli/app.py

@@ -261,7 +261,7 @@ def main() -> None:
             args = p.parse_args(av[3:])
             sys.exit(cmd_platform_ensure(
                 key=args.key,
-                display_name=args.display_name or args.key,
+                display_name=args.display_name,
                 domain=args.domain,
                 url=args.url,
                 auth_strategy=args.auth_strategy,