fix(background-agent): force TUI update when notifying parent session

- Use `promptAsync` instead of `prompt` to avoid session state conflicts
- Use `tui.showToast` for immediate visible feedback
- Hack: Trigger `tui.submitPrompt` after message injection to force TUI refresh and trigger AI response
- Update `BackgroundManager` to accept `PluginInput` for directory access

src/index.ts

@@ -164,7 +164,7 @@ const OhMyOpenCodePlugin: Plugin = async (ctx) => {
 
   updateTerminalTitle({ sessionId: "main" });
 
-  const backgroundManager = new BackgroundManager(ctx.client);
+  const backgroundManager = new BackgroundManager(ctx);
 
   const backgroundNotificationHook = createBackgroundNotificationHook(backgroundManager);
   const backgroundTools = createBackgroundTools(backgroundManager, ctx.client);