debug: add console logging for court sport variation initialization

Added debug logging to investigate sport variation dropdown issue:
- Log court data object on mount
- Log extracted sport_variation_id value
- Added visual disabled state (gray background) for locked dropdown
- Extracted initialSportVariationId to const for better debugging

This will help identify if:
1. Court data has sport_variation nested structure
2. sport_variation_id is being extracted correctly
3. Dropdown value is being set properly

Related: BUILD #21 sport variation display issue

src/app/[locale]/admin/clubs/[club_id]/tabs/ClubCourtsTab.tsx

@@ -253,9 +253,8 @@ function CourtFormModal({ clubId, court, onClose, onSuccess }: CourtFormModalPro
   const isEditing = !!court;
   const [name, setName] = useState(court?.name || '');
   // Get sport_variation_id from nested structure or fall back to deprecated flat field
-  const [sportVariationId, setSportVariationId] = useState<number>(
-    court?.sport_variation?.sport_variation_id || court?.sport_variation_id || 0
-  );
+  const initialSportVariationId = court?.sport_variation?.sport_variation_id || court?.sport_variation_id || 0;
+  const [sportVariationId, setSportVariationId] = useState<number>(initialSportVariationId);
   const [sports, setSports] = useState<Sport[]>([]);
   const [loadingSports, setLoadingSports] = useState(true);
   const [saving, setSaving] = useState(false);
@@ -263,6 +262,12 @@ function CourtFormModal({ clubId, court, onClose, onSuccess }: CourtFormModalPro
   const [fieldError, setFieldError] = useState('');
   const [sportVariationError, setSportVariationError] = useState('');
 
+  // Debug: log the court data and extracted sport variation ID
+  useEffect(() => {
+    console.log('Court data:', court);
+    console.log('Extracted sport_variation_id:', initialSportVariationId);
+  }, [court]);
+
   useEffect(() => {
     async function loadSports() {
       setLoadingSports(true);
@@ -395,7 +400,7 @@ function CourtFormModal({ clubId, court, onClose, onSuccess }: CourtFormModalPro
                   sportVariationError
                     ? 'border-red-300 focus:border-red-500'
                     : 'border-slate-200 focus:border-slate-900'
-                } focus:outline-none`}
+                } focus:outline-none ${(saving || isEditing) ? 'bg-slate-100 cursor-not-allowed' : ''}`}
                 disabled={saving || isEditing}
               >
                 <option value={0} disabled>Select sport variation</option>