feat(10-02): mount KB and calendar routers, update tool registry and prompt builder

- Mount kb_router and calendar_auth_router on gateway (Phase 10 agent capabilities)
- Update calendar_lookup tool schema with action/event_summary/event_start/event_end params
- Add tool result formatting instruction to build_system_prompt when tools assigned (CAP-06)
- Add kb_router and calendar_auth_router to shared/api/__init__.py exports
- Confirm CAP-04 (http_request) and CAP-07 (audit logging) already working

packages/shared/shared/api/__init__.py

@@ -5,9 +5,11 @@ Import and mount these routers in service main.py files.
 """
 
 from shared.api.billing import billing_router, webhook_router
+from shared.api.calendar_auth import calendar_auth_router
 from shared.api.channels import channels_router
 from shared.api.chat import chat_router
 from shared.api.invitations import invitations_router
+from shared.api.kb import kb_router
 from shared.api.llm_keys import llm_keys_router
 from shared.api.portal import portal_router
 from shared.api.push import push_router
@@ -25,4 +27,6 @@ __all__ = [
     "templates_router",
     "chat_router",
     "push_router",
+    "kb_router",
+    "calendar_auth_router",
 ]