Conversation drawer shows the previous attack's conversations after switching attacks #3575

Description

The conversation panel keeps a single component instance across attack switches, and its state reset block only clears the loaded conversations when the new attack id is null. Switching from one attack to another therefore leaves the previous attack's conversation list rendered under the new attack's header until the new fetch resolves, with no loading indicator.

During that window a row click hands the old attack's conversation id to the new attack's context, and the star action can promote an old attack's conversation as the new attack's main conversation. The Chat route keeps the panel mounted across attack changes and forces the drawer open whenever related conversations exist, so the stale window is directly reachable by navigating between attacks.

Expected Behavior

Switching attacks should clear the previous attack's conversations, clear the main id and error, and show the loading state until the new attack's conversations resolve, mirroring the mount behavior.

Reproduction Steps

1. Open an attack with conversations and the conversation drawer open.
2. Navigate to a second attack.
3. The drawer immediately shows the first attack's conversations under the second attack's header.

Minimal Reproduction

The render phase reset in ConversationPanel.tsx gates every setter behind if (!attackResultId).

Environment

PyRIT main.