fix(admin): duration validation + sport variation display

Fixed two issues reported by user:

1. Slot definition duration validation error:
   - Changed step from "15" to "1" on duration input
   - HTML5 validation was failing because with min="1" and step="15",
     valid values were 1, 16, 31, 46, 61, 76, 91... (not 90!)
   - Now accepts any integer duration >= 1 minute
   - Error "nearest 76 or 91" resolved

2. Sport variation not showing in court edit form:
   - Updated Court type to include nested sport_variation structure
   - Backend now returns full sport_variation object with sport details
   - Updated CourtFormModal to extract sport_variation_id from nested
     structure: court.sport_variation.sport_variation_id
   - Added sport variation display in court list (e.g., "Padel - Indoor")
   - Maintains backward compatibility with deprecated flat field

Changes:
- SlotDefinitionForm: step="1" instead of step="15"
- Court interface: added optional sport_variation nested object
- ClubCourtsTab: reads sport_variation_id from nested structure
- ClubCourtsTab: displays "Sport - Variation" in court list

Related: Backend Brooke nested sport_variation response structure

src/app/[locale]/admin/clubs/[club_id]/slot-definitions/SlotDefinitionForm.tsx

@@ -240,7 +240,7 @@ export default function SlotDefinitionForm({
                 value={durationMinutes}
                 onChange={(e) => setDurationMinutes(parseInt(e.target.value) || 0)}
                 min="1"
-                step="15"
+                step="1"
                 className={`w-full px-4 py-3 border-2 rounded-lg font-medium transition-colors ${
                   errors.duration_minutes
                     ? 'border-red-300 focus:border-red-500'

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

@@ -164,10 +164,17 @@ export default function ClubCourtsTab({ clubId }: ClubCourtsTabProps) {
                   <h3 className="text-xl font-bold text-slate-900 mb-2">
                     {court.name}
                   </h3>
+                  <div className="space-y-1">
+                    {court.sport_variation && (
+                      <p className="text-sm font-medium text-slate-700">
+                        {court.sport_variation.sport.name} - {court.sport_variation.name}
+                      </p>
+                    )}
                     <p className="text-sm text-slate-600">
                       ID: {court.court_id} · Created {formatTimestamp(court.created_at)}
                     </p>
                   </div>
+                </div>
 
                 <div className="flex items-center space-x-2">
                   <button
@@ -245,7 +252,10 @@ interface CourtFormModalProps {
 function CourtFormModal({ clubId, court, onClose, onSuccess }: CourtFormModalProps) {
   const isEditing = !!court;
   const [name, setName] = useState(court?.name || '');
-  const [sportVariationId, setSportVariationId] = useState<number>(court?.sport_variation_id || 0);
+  // 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 [sports, setSports] = useState<Sport[]>([]);
   const [loadingSports, setLoadingSports] = useState(true);
   const [saving, setSaving] = useState(false);

src/types/courts.ts

@@ -7,7 +7,17 @@
 export interface Court {
   court_id: number;
   name: string;
+  sport_variation_id?: number; // For backward compatibility (deprecated)
+  sport_variation?: {
     sport_variation_id: number;
+    name: string;
+    slug: string;
+    sport: {
+      sport_id: number;
+      name: string;
+      slug: string;
+    };
+  };
   created_at: string; // ISO 8601 timestamp
   updated_at: string; // ISO 8601 timestamp
 }