Add read-only Google Calendar integration via gws CLI

Adds a get_calendar_events agent tool that shells out to `gws calendar +agenda`
for admin users. Controlled by GOOGLE_CALENDAR_ENABLED env var, with OAuth
credentials mounted from credentials.json.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

blueprints/conversation/__init__.py

@@ -96,7 +96,9 @@ async def query():
         conversation, query, system_prompt=system_prompt
     )
     payload = {"messages": messages_payload}
-    agent_config = {"configurable": {"user_id": str(user.id)}}
+    agent_config = {
+        "configurable": {"user_id": str(user.id), "is_admin": user.is_admin()}
+    }
 
     response = await main_agent.ainvoke(payload, config=agent_config)
     message = response.get("messages", [])[-1].content
@@ -183,7 +185,9 @@ async def stream_query():
         conversation, query_text or "", image_description, system_prompt=system_prompt
     )
     payload = {"messages": messages_payload}
-    agent_config = {"configurable": {"user_id": str(user.id)}}
+    agent_config = {
+        "configurable": {"user_id": str(user.id), "is_admin": user.is_admin()}
+    }
 
     async def event_generator():
         final_message = None