Fix wellness sync crash: serialize intraday_hr as JSON string for psycopg2

psycopg2 treats Python lists as PostgreSQL arrays (bigint[]) rather than JSON,
causing a DatatypeMismatch error on the json/jsonb column. Serializing with
json.dumps() before the raw SQL INSERT fixes the type error.

Also wrap per-day INSERT in try/except+rollback so one bad day doesn't abort
the entire session, and add db.rollback() in tasks.py after sync_wellness
failure so the final status-update commit can always succeed.

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

backend/app/services/garmin_connect_sync.py

@@ -253,6 +253,12 @@ def sync_wellness(garmin, user_id: int, since: Optional[datetime], db,
         if not row:
             continue
 
+        # psycopg2 treats Python lists as PostgreSQL arrays; serialize JSON columns
+        # explicitly so they arrive as a JSON string that the json/jsonb column accepts.
+        import json as _json
+        if "intraday_hr" in row and isinstance(row["intraday_hr"], list):
+            row["intraday_hr"] = _json.dumps(row["intraday_hr"])
+
         cols = list(row.keys())
         col_sql  = ", ".join(cols)
         val_sql  = ", ".join(f":{c}" for c in cols)
@@ -267,13 +273,17 @@ def sync_wellness(garmin, user_id: int, since: Optional[datetime], db,
         params = {"user_id": user_id, "day": day.isoformat()}
         params.update(row)
 
-        db.execute(text(f"""
-            INSERT INTO health_metrics (user_id, date, {col_sql})
-            VALUES (:user_id, :day, {val_sql})
-            ON CONFLICT (user_id, date) DO UPDATE SET {upd_sql}
-        """), params)
-        db.commit()
-        processed += 1
+        try:
+            db.execute(text(f"""
+                INSERT INTO health_metrics (user_id, date, {col_sql})
+                VALUES (:user_id, :day, {val_sql})
+                ON CONFLICT (user_id, date) DO UPDATE SET {upd_sql}
+            """), params)
+            db.commit()
+            processed += 1
+        except Exception as exc:
+            logger.warning("Failed to upsert health_metrics for %s: %s", day_str, exc)
+            db.rollback()
 
     return processed