Trace scheduled, webhook, search, MCP and graph-extraction runs

run_agent_headless records each unattended run under its endpoint; the
scheduler passes its run id and the webhook worker its task id so Logs rows
can find their trace, while the LLM's own request id stays untouched for
quota counts. /api/search and MCP search_docs record their retrieval, and a
graph build records every extraction call under one step.

docsgpt/mcp_server.py

@@ -53,7 +53,7 @@ async def search_docs(query: str, chunks: int = 5) -> list[dict]:
     if not api_key:
         raise PermissionError("Missing Bearer token")
     try:
-        return await asyncio.to_thread(search, api_key, query, chunks)
+        return await asyncio.to_thread(search, api_key, query, chunks, source="mcp")
     except InvalidAPIKey as exc:
         raise PermissionError("Invalid API key") from exc
     except SearchFailed: