fix: telemetry heartbeat insert needs an explicit uuid id (NOT NULL, no default)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

nightly_tune.py

@@ -46,10 +46,11 @@ def _write_heartbeat(outcome: str) -> None:
     # The DB row is queryable remotely and survives container churn.
     try:
         con = open_research_db("market")
+        import uuid
         con.execute(
-            "INSERT INTO telemetry_events (event_type, source, reason, metadata_json) "
-            "VALUES (?, ?, ?, ?)",
-            ["tuner_heartbeat", "nightly_tune", outcome,
+            "INSERT INTO telemetry_events (id, event_type, source, reason, metadata_json) "
+            "VALUES (?, ?, ?, ?, ?)",
+            [str(uuid.uuid4()), "tuner_heartbeat", "nightly_tune", outcome,
              json.dumps({"ran_at": datetime.now(timezone.utc).isoformat()})])
     except Exception:  # noqa: BLE001
         pass