feat(background-agent): integrate into main plugin

🤖 GENERATED WITH ASSISTANCE OF [OhMyOpenCode](https://github.com/code-yeongyu/oh-my-opencode)

src/hooks/background-notification/index.ts

@@ -15,7 +15,7 @@ interface ChatMessageInput {
 }
 
 interface ChatMessageOutput {
-  parts: Array<{ type: string; text: string }>
+  parts: Array<{ type: string; text?: string; [key: string]: unknown }>
   [key: string]: unknown
 }
 

src/hooks/index.ts

@@ -11,3 +11,4 @@ export { createAnthropicAutoCompactHook } from "./anthropic-auto-compact";
 export { createThinkModeHook } from "./think-mode";
 export { createClaudeCodeHooksHook } from "./claude-code-hooks";
 export { createRulesInjectorHook } from "./rules-injector";
+export { createBackgroundNotificationHook } from "./background-notification";