feat(plugin): integrate omo_task tool and prevent recursion in subagents

Register omo_task tool in main plugin and disable it for explore/librarian agents to prevent infinite recursion.

- Export createOmoTask from src/tools/index.ts
- Initialize omo_task in main plugin with ctx
- Spread omo_task into builtinTools export
- Add recursion prevention: disable omo_task tool for explore agent config
- Add recursion prevention: disable omo_task tool for librarian agent config

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

src/tools/index.ts

@@ -22,6 +22,8 @@ import { glob } from "./glob"
 import { slashcommand } from "./slashcommand"
 import { skill } from "./skill"
 
+export { createOmoTask } from "./omo-task"
+
 export const builtinTools = {
   lsp_hover,
   lsp_goto_definition,