refactor: migrate delegate_task to task tool with metadata fixes

- Rename delegate_task tool to task across codebase (100 files)
- Update model references: claude-opus-4-6 → 4-5, gpt-5.3-codex → 5.2-codex
- Add tool-metadata-store to restore metadata overwritten by fromPlugin()
- Add session ID polling for BackgroundManager task sessions
- Await async ctx.metadata() calls in tool executors
- Add ses_ prefix guard to getMessageDir for performance
- Harden BackgroundManager with idle deferral and error handling
- Fix duplicate task key in sisyphus-junior test object literals
- Fix unawaited showOutputToUser in ast_grep_replace
- Fix background=true → run_in_background=true in ultrawork prompt
- Fix duplicate task/task references in docs and comments

src/hooks/task-resume-info/index.ts

@@ -1,4 +1,4 @@
-const TARGET_TOOLS = ["task", "Task", "task_tool", "call_omo_agent", "delegate_task"]
+const TARGET_TOOLS = ["task", "Task", "task_tool", "call_omo_agent"]
 
 const SESSION_ID_PATTERNS = [
   /Session ID: (ses_[a-zA-Z0-9_-]+)/,
@@ -27,7 +27,7 @@ export function createTaskResumeInfoHook() {
      const sessionId = extractSessionId(output.output)
      if (!sessionId) return
 
-     output.output = output.output.trimEnd() + `\n\nto continue: delegate_task(session_id="${sessionId}", prompt="...")`
+     output.output = output.output.trimEnd() + `\n\nto continue: task(session_id="${sessionId}", prompt="...")`
    }
 
    return {