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/nanobot/__main__.py

@@ -0,0 +1,8 @@
+"""
+Entry point for running nanobot as a module: python -m nanobot
+"""
+
+from nanobot.cli.commands import app
+
+if __name__ == "__main__":
+    app()