fix: wrap rest_config dict with Json() for psycopg2 JSONB insert

Error: psycopg2.ProgrammingError: can't adapt type 'dict'
Solution: Import psycopg2.extras.Json and wrap config_dict

Changes:
- Import Json from psycopg2.extras
- Wrap config_dict with Json() in INSERT
- Wrap config_dict with Json() in UPDATE

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

backend/routers/rest_days.py

@@ -9,6 +9,7 @@ from datetime import datetime, timedelta
 
 from fastapi import APIRouter, HTTPException, Depends, Header
 from pydantic import BaseModel, Field
+from psycopg2.extras import Json
 
 from db import get_db, get_cursor, r2d
 from auth import require_auth
@@ -103,7 +104,7 @@ def create_rest_day(
                 note = EXCLUDED.note
             RETURNING id, profile_id, date, rest_config, note, created_at
             """,
-            (pid, data.date, config_dict, data.note)
+            (pid, data.date, Json(config_dict), data.note)
         )
 
         result = cur.fetchone()
@@ -161,7 +162,7 @@ def update_rest_day(
 
     if data.rest_config:
         updates.append("rest_config = %s")
-        values.append(data.rest_config.model_dump())
+        values.append(Json(data.rest_config.model_dump()))
 
     if data.note is not None:
         updates.append("note = %s")