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.

nanobot/cli/commands.py

@@ -593,6 +593,7 @@ def serve(
         unified_session=runtime_config.agents.defaults.unified_session,
         disabled_skills=runtime_config.agents.defaults.disabled_skills,
         session_ttl_minutes=runtime_config.agents.defaults.session_ttl_minutes,
+        tools_config=runtime_config.tools,
     )
 
     model_name = runtime_config.agents.defaults.model
@@ -687,6 +688,7 @@ def gateway(
         unified_session=config.agents.defaults.unified_session,
         disabled_skills=config.agents.defaults.disabled_skills,
         session_ttl_minutes=config.agents.defaults.session_ttl_minutes,
+        tools_config=config.tools,
     )
 
     # Set cron callback (needs agent)
@@ -964,6 +966,7 @@ def agent(
         unified_session=config.agents.defaults.unified_session,
         disabled_skills=config.agents.defaults.disabled_skills,
         session_ttl_minutes=config.agents.defaults.session_ttl_minutes,
+        tools_config=config.tools,
     )
     restart_notice = consume_restart_notice_from_env()
     if restart_notice and should_show_cli_restart_notice(restart_notice, session_id):