feat: stdin.ref/unref, raw mode default false, conditional listener, maxListeners

- stdin.ref() on raw mode enable, stdin.unref() on disable
- setEncoding("utf8") on raw mode enable
- Raw mode default changed from true to false (hooks acquire it)
- useStdin().setRawMode routed through ref-counted controller
- Stdin listeners attached only when raw mode is active
- EventEmitter maxListeners set to Infinity

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/testing/src/streams.ts

@@ -34,5 +34,7 @@ export function makeFakeStdin(): { stream: NodeJS.ReadStream; rawMode: RawModeSt
       return this;
     },
   });
+  (s as any).ref = () => {};
+  (s as any).unref = () => {};
   return { stream: s, rawMode };
 }