feat: add terminal title and progress indicator for approval screens (#499)

Co-authored-by: Letta <noreply@letta.com>

src/cli/hooks/useProgressIndicator.ts

@@ -0,0 +1,45 @@
+import { useEffect } from "react";
+
+/**
+ * Shows an indeterminate progress indicator in the terminal tab/taskbar
+ * while the component is mounted (useful for "waiting for user" states).
+ *
+ * Uses OSC 9;4 (ConEmu progress bar sequence) supported by:
+ * - iTerm2
+ * - Windows Terminal
+ * - ConEmu
+ * - gnome-terminal (VTE)
+ *
+ * Format: ESC ] 9 ; 4 ; <state> ; <progress> BEL
+ * States:
+ *   0 = hidden (clear)
+ *   1 = normal progress
+ *   2 = error state
+ *   3 = indeterminate (animated)
+ *   4 = warning state
+ */
+
+// Show indeterminate progress (animated green bar)
+const PROGRESS_INDETERMINATE = "\x1b]9;4;3;0\x07";
+// Clear/hide progress
+const PROGRESS_CLEAR = "\x1b]9;4;0;0\x07";
+
+/**
+ * Hook that shows an indeterminate progress indicator while mounted.
+ * Clears the indicator when the component unmounts.
+ *
+ * @param active - Whether the indicator should be shown (default: true)
+ */
+export function useProgressIndicator(active = true): void {
+  useEffect(() => {
+    if (!active) return;
+
+    // Show indeterminate progress on mount
+    process.stdout.write(PROGRESS_INDETERMINATE);
+
+    // Clear progress on unmount
+    return () => {
+      process.stdout.write(PROGRESS_CLEAR);
+    };
+  }, [active]);
+}