feat: [equipment] 설비점검 조회 응답에 휴무일(non_working_days) 추가

- InspectionCycle::getHolidayDates()로 해당 주기/기간의 휴무일 조회
- 응답에 non_working_days 배열 포함하여 프론트 캘린더 표시 지원

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

app/Services/Equipment/EquipmentInspectionService.php

@@ -34,6 +34,9 @@ public function getInspections(string $cycle, string $period, ?string $productio
         $labels = InspectionCycle::columnLabels($cycle, $period);
         $userId = $this->apiUserId();
 
+        $tenantId = $this->tenantId();
+        $holidayDates = InspectionCycle::getHolidayDates($cycle, $period, $tenantId);
+
         $result = [];
 
         foreach ($equipments as $equipment) {
@@ -68,6 +71,7 @@ public function getInspections(string $cycle, string $period, ?string $productio
                 'details' => $details,
                 'labels' => $labels,
                 'can_inspect' => $equipment->canInspect($userId),
+                'non_working_days' => array_keys($holidayDates),
             ];
         }