feat(paste): add large paste placeholder and fix enter-submit on macOS

- Add large paste placeholder feature: when pasting text > 1000 chars,
  show a placeholder like '[Pasted Content 1500 chars]' instead of the
  full content. The full text is stored and expanded on submit.

- Fix enter-submit on macOS: only apply recentPasteTime protection when
  pasteWorkaround is enabled (Windows or Node < 20). On macOS/Linux with
  modern Node, bracketed paste markers work reliably so the protection is
  unnecessary and caused the first Enter after paste to be ignored.

Co-authored-by: Qwen-Coder <qwen-coder@alibabacloud.com>

packages/cli/src/ui/contexts/KeypressContext.tsx

@@ -60,6 +60,7 @@ export type KeypressHandler = (key: Key) => void;
 interface KeypressContextValue {
   subscribe: (handler: KeypressHandler) => void;
   unsubscribe: (handler: KeypressHandler) => void;
+  pasteWorkaround: boolean;
 }
 
 const KeypressContext = createContext<KeypressContextValue | undefined>(
@@ -799,7 +800,9 @@ export function KeypressProvider({
   ]);
 
   return (
-    <KeypressContext.Provider value={{ subscribe, unsubscribe }}>
+    <KeypressContext.Provider
+      value={{ subscribe, unsubscribe, pasteWorkaround }}
+    >
       {children}
     </KeypressContext.Provider>
   );