Fix hook message duplication in TUI

Two bugs:
1. createCustomMessage was returning role: 'user' instead of preserving
   the hook message structure (role: 'hookMessage', customType, etc.)
2. rebuildChatFromMessages wasn't clearing the container before rebuilding

packages/coding-agent/src/modes/interactive/interactive-mode.ts

@@ -1208,6 +1208,7 @@ export class InteractiveMode {
 	}
 
 	private rebuildChatFromMessages(): void {
+		this.chatContainer.clear();
 		const context = this.sessionManager.buildSessionContext();
 		this.renderSessionContext(context);
 	}