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_cron_service.py

@@ -0,0 +1,61 @@
+import asyncio
+
+import pytest
+
+from nanobot.cron.service import CronService
+from nanobot.cron.types import CronSchedule
+
+
+def test_add_job_rejects_unknown_timezone(tmp_path) -> None:
+    service = CronService(tmp_path / "cron" / "jobs.json")
+
+    with pytest.raises(ValueError, match="unknown timezone 'America/Vancovuer'"):
+        service.add_job(
+            name="tz typo",
+            schedule=CronSchedule(kind="cron", expr="0 9 * * *", tz="America/Vancovuer"),
+            message="hello",
+        )
+
+    assert service.list_jobs(include_disabled=True) == []
+
+
+def test_add_job_accepts_valid_timezone(tmp_path) -> None:
+    service = CronService(tmp_path / "cron" / "jobs.json")
+
+    job = service.add_job(
+        name="tz ok",
+        schedule=CronSchedule(kind="cron", expr="0 9 * * *", tz="America/Vancouver"),
+        message="hello",
+    )
+
+    assert job.schedule.tz == "America/Vancouver"
+    assert job.state.next_run_at_ms is not None
+
+
+@pytest.mark.asyncio
+async def test_running_service_honors_external_disable(tmp_path) -> None:
+    store_path = tmp_path / "cron" / "jobs.json"
+    called: list[str] = []
+
+    async def on_job(job) -> None:
+        called.append(job.id)
+
+    service = CronService(store_path, on_job=on_job)
+    job = service.add_job(
+        name="external-disable",
+        schedule=CronSchedule(kind="every", every_ms=200),
+        message="hello",
+    )
+    await service.start()
+    try:
+        # Wait slightly to ensure file mtime is definitively different
+        await asyncio.sleep(0.05)
+        external = CronService(store_path)
+        updated = external.enable_job(job.id, enabled=False)
+        assert updated is not None
+        assert updated.enabled is False
+
+        await asyncio.sleep(0.35)
+        assert called == []
+    finally:
+        service.stop()