feat(ai): temporal worker for lesson plan workflow

- deploy temporal server (postgresql + auto-setup + ui) in docker-compose
- new temporal/ module: workflow + activities + worker manager
- convert lesson plan 4-step orchestration to temporal workflow
- activities wrap existing analyze/recommend/generate/prepare_review steps
- worker injects failover_chain/content_client/data_ana_client via module globals
- start() uses temporal client.start_workflow, falls back to asyncio in dev
- register temporal ports 7233/8085 in port-allocation

Implements M6.5 of v2.1 migration plan (ADR-030).

services/ai/pyproject.toml

@@ -22,6 +22,8 @@ dependencies = [
     "tenacity>=9.0.0",
     # GraphQL Federation 2 子图（v2.1 M1，Apollo Router 组合）
     "strawberry-graphql[asgi]>=0.257.0",
+    # Temporal 工作流引擎（v2.1 §8.2 ADR-030，AI 耗时工作流）
+    "temporalio>=1.7.0",
 ]
 
 [tool.uv.sources]