feat(agent): add SelfTool for runtime self-inspection and configuration

Add a built-in tool that lets the agent inspect and modify its own
runtime state (model, iterations, context window, etc.).

Key features:
- inspect: view current config, usage stats, and subagent status
- modify: adjust parameters at runtime (protected by type/range validation)
- Subagent observability: inspect running subagent tasks (phase,
  iteration, tool events, errors) — subagents are no longer a black box
- Watchdog corrects out-of-bounds values on each iteration
- Enabled by default in read-only mode (self_modify: false)
- All changes are in-memory only; restart restores defaults
- Comprehensive test suite (90 tests)

Includes a self-awareness skill (always-on) with progressive disclosure:
SKILL.md for core rules, references/examples.md for detailed scenarios.

tests/tools/test_search_tools.py

@@ -3,6 +3,7 @@
 from __future__ import annotations
 
 import os
+import time
 from pathlib import Path
 from types import SimpleNamespace
 from unittest.mock import AsyncMock, MagicMock
@@ -10,7 +11,7 @@ from unittest.mock import AsyncMock, MagicMock
 import pytest
 
 from nanobot.agent.loop import AgentLoop
-from nanobot.agent.subagent import SubagentManager
+from nanobot.agent.subagent import SubagentManager, SubagentStatus
 from nanobot.agent.tools.search import GlobTool, GrepTool
 from nanobot.bus.queue import MessageBus
 
@@ -319,7 +320,8 @@ async def test_subagent_registers_grep_and_glob(tmp_path: Path) -> None:
     mgr.runner.run = fake_run
     mgr._announce_result = AsyncMock()
 
-    await mgr._run_subagent("sub-1", "search task", "label", {"channel": "cli", "chat_id": "direct"})
+    status = SubagentStatus(task_id="sub-1", label="label", task_description="search task", started_at=time.monotonic())
+    await mgr._run_subagent("sub-1", "search task", "label", {"channel": "cli", "chat_id": "direct"}, status)
 
     assert "grep" in captured["tool_names"]
     assert "glob" in captured["tool_names"]