feat(API): 부실채권, 재고, 입고 기능 개선

- BadDebt 컨트롤러/서비스 기능 확장
- StockService 재고 조회 로직 개선
- ProcessReceivingRequest 검증 규칙 수정
- Item, Order, CommonCode, Shipment 모델 업데이트
- TodayIssueObserverService 개선

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/Http/Controllers/Api/V1/BadDebtController.php

@@ -18,14 +18,15 @@ public function __construct(
     ) {}
 
     /**
-     * 악성채권 목록
+     * 악성채권 목록 (거래처 기준)
+     *
+     * 거래처별 활성 악성채권 집계 목록을 반환
      */
     public function index(Request $request)
     {
         $params = $request->only([
             'client_id',
             'status',
-            'is_active',
             'search',
             'sort_by',
             'sort_dir',
@@ -33,9 +34,54 @@ public function index(Request $request)
             'page',
         ]);
 
-        $badDebts = $this->service->index($params);
+        $clients = $this->service->index($params);
 
-        return ApiResponse::success($badDebts, __('message.fetched'));
+        // 거래처 기준 응답으로 변환
+        $transformedData = $clients->through(function ($client) {
+            // 가장 최근 활성 악성채권 정보
+            $latestBadDebt = $client->activeBadDebts->first();
+
+            return [
+                'id' => $client->id,
+                'client_id' => $client->id,
+                'client_code' => $client->client_code,
+                'client_name' => $client->name,
+                'business_no' => $client->business_no,
+                'contact_person' => $client->contact_person,
+                'phone' => $client->phone,
+                'mobile' => $client->mobile,
+                'email' => $client->email,
+                'address' => $client->address,
+                'client_type' => $client->client_type,
+                // 집계 데이터
+                'total_debt_amount' => (float) ($client->total_debt_amount ?? 0),
+                'max_overdue_days' => (int) ($client->max_overdue_days ?? 0),
+                'bad_debt_count' => (int) ($client->active_bad_debt_count ?? 0),
+                // 대표 상태 (가장 최근 악성채권의 상태)
+                'status' => $latestBadDebt?->status ?? 'collecting',
+                'is_active' => true, // 리스트에 나온 건 모두 활성
+                // 담당자 (가장 최근 악성채권의 담당자)
+                'assigned_user' => $latestBadDebt?->assignedUser ? [
+                    'id' => $latestBadDebt->assignedUser->id,
+                    'name' => $latestBadDebt->assignedUser->name,
+                ] : null,
+                // 개별 악성채권 목록
+                'bad_debts' => $client->activeBadDebts->map(fn ($bd) => [
+                    'id' => $bd->id,
+                    'debt_amount' => (float) $bd->debt_amount,
+                    'status' => $bd->status,
+                    'overdue_days' => $bd->overdue_days,
+                    'is_active' => $bd->is_active,
+                    'occurred_at' => $bd->occurred_at?->toDateString(),
+                    'assigned_user' => $bd->assignedUser ? [
+                        'id' => $bd->assignedUser->id,
+                        'name' => $bd->assignedUser->name,
+                    ] : null,
+                ])->toArray(),
+            ];
+        });
+
+        return ApiResponse::success($transformedData, __('message.fetched'));
     }
 
     /**