feat(coding-agent): watch .git/HEAD for branch changes (#79)

Auto-updates footer when git branch changes externally (e.g., git checkout in another terminal)

packages/coding-agent/src/tui/tui-renderer.ts

@@ -464,6 +464,11 @@ export class TuiRenderer {
 			this.updateEditorBorderColor();
 			this.ui.requestRender();
 		});
+
+		// Set up git branch watcher
+		this.footer.watchBranch(() => {
+			this.ui.requestRender();
+		});
 	}
 
 	private subscribeToAgent(): void {
@@ -1523,6 +1528,7 @@ export class TuiRenderer {
 			this.loadingAnimation.stop();
 			this.loadingAnimation = null;
 		}
+		this.footer.dispose();
 		if (this.isInitialized) {
 			this.ui.stop();
 			this.isInitialized = false;