feat: add official Codex skill and harden task execution

Install and update artemis-use with task diagnostics and plugin guidance. Preserve cross-device file receipts, review canonical reports, guard stage transitions and reduce small history summaries. Improve exploration lifecycle, request recovery and browser live connections.

tests/unit/mcp/conftest.py

@@ -66,7 +66,15 @@ def shared_mcp_backend(tmp_path, monkeypatch):
             key: registration.info[key] for key in ("protocol", "installation", "instance", "pid")
         }
 
-    server = uvicorn.Server(uvicorn.Config(app, host="127.0.0.1", port=port, log_level="error"))
+    server = uvicorn.Server(
+        uvicorn.Config(
+            app,
+            host="127.0.0.1",
+            port=port,
+            log_level="error",
+            timeout_graceful_shutdown=5,  # Match the user-started service's SSE shutdown budget.
+        )
+    )
     thread = threading.Thread(target=server.run, kwargs={"sockets": [listener]}, daemon=True)
     thread.start()
     deadline = time.monotonic() + 8