fix: add start_date and created_at to get_active_goals query

ROOT CAUSE: get_active_goals() SELECT was missing start_date and created_at
IMPACT: Time-based deviation calculation failed silently for all goals

Now returns:
- start_date: Required for accurate time-based progress calculation
- created_at: Fallback when start_date is not set

This fixes:
- Zielgewicht (weight) should now show +7% ahead
- Körperfett should show time deviation
- All goals with target_date now have time-based tracking

backend/goal_utils.py

@@ -542,7 +542,8 @@ def get_active_goals(profile_id: str) -> List[Dict]:
         cur = get_cursor(conn)
         cur.execute("""
             SELECT id, goal_type, name, target_value, target_date,
-                   current_value, start_value, progress_pct, status, is_primary
+                   current_value, start_value, start_date, progress_pct,
+                   status, is_primary, created_at
             FROM goals
             WHERE profile_id = %s
               AND status IN ('active', 'in_progress')