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/tests/test_base_channel.py

@@ -0,0 +1,25 @@
+from types import SimpleNamespace
+
+from nanobot.bus.events import OutboundMessage
+from nanobot.bus.queue import MessageBus
+from nanobot.channels.base import BaseChannel
+
+
+class _DummyChannel(BaseChannel):
+    name = "dummy"
+
+    async def start(self) -> None:
+        return None
+
+    async def stop(self) -> None:
+        return None
+
+    async def send(self, msg: OutboundMessage) -> None:
+        return None
+
+
+def test_is_allowed_requires_exact_match() -> None:
+    channel = _DummyChannel(SimpleNamespace(allow_from=["allow@email.com"]), MessageBus())
+
+    assert channel.is_allowed("allow@email.com") is True
+    assert channel.is_allowed("attacker|allow@email.com") is False