fix(tui): restore clipboard hotkeys in clarify mode

ui-tui/src/lib/clipboard.ts

@@ -0,0 +1,30 @@
+import { spawnSync, type SpawnSyncOptions } from 'node:child_process'
+
+const DEFAULT_SPAWN_OPTS: SpawnSyncOptions = {
+  stdio: ['ignore', 'pipe', 'ignore'],
+  encoding: 'utf8'
+}
+
+/**
+ * Read plain text from the system clipboard.
+ *
+ * On macOS this uses `pbpaste`. On other platforms we intentionally return
+ * null for now; the TUI's text-paste hotkeys are primarily targeted at the
+ * macOS clarify/input flow.
+ */
+export function readClipboardText(
+  platform: NodeJS.Platform = process.platform,
+  run = spawnSync
+): string | null {
+  if (platform !== 'darwin') {
+    return null
+  }
+
+  const result = run('pbpaste', [], DEFAULT_SPAWN_OPTS)
+
+  if (result.status !== 0 || typeof result.stdout !== 'string') {
+    return null
+  }
+
+  return result.stdout
+}