feat: 新增 core/agents 模块和 nanobot

- 新增 agents 模块，包含 agent、api、skills 等子模块
- 新增 nanobot 项目，支持多渠道集成
- 添加启动脚本 start-all.bat 和 start-all.sh

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

core/nanobot/.gitignore

@@ -0,0 +1,24 @@
+.worktrees/
+.assets
+.env
+*.pyc
+dist/
+build/
+docs/
+*.egg-info/
+*.egg
+*.pyc
+*.pyo
+*.pyd
+*.pyw
+*.pyz
+*.pywz
+*.pyzz
+.venv/
+venv/
+__pycache__/
+poetry.lock
+.pytest_cache/
+botpy.log
+nano.*.save
+