fix(types): clear host mypy debt and prevent typing regressions

严格检查全部宿主源码，清零类型错误预算并移除按模块类型豁免。
按原因、所属方法、错误码及语法指纹锁定必要兼容例外和站点类型桩，
CI 阻断新增忽略、检查范围退化、本地桩替代真实接口及新的类型错误。

修复空值、异步和供应方类型边界，保持插件与 API 兼容合同，
并补充存储、订阅、通知、Agent 和工作流边界的回归覆盖。

.github/workflows/test.yml

@@ -106,7 +106,10 @@ jobs:
       - name: Install dependencies
         run: uv sync --locked
 
-      - name: Check governed Python types
+      - name: Check exact typing compatibility exceptions
+        run: uv run --locked --no-sync python scripts/architecture/mypy_policy.py
+
+      - name: Check all host Python types
         run: uv run --locked --no-sync mypy --config-file mypy.ini
 
       - name: Check structural complexity ratchet