feat: [stock] 재고 조정 API 추가

- GET /stocks/{id}/adjustments: 조정 이력 조회
- POST /stocks/{id}/adjustments: 조정 등록 (증감 수량 + 사유)
- StockTransaction에 adjustment reason 추가
- StoreStockAdjustmentRequest 검증 추가

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

@@ -4,6 +4,7 @@
 
 use App\Helpers\ApiResponse;
 use App\Http\Controllers\Controller;
+use App\Http\Requests\V1\Stock\StoreStockAdjustmentRequest;
 use App\Services\StockService;
 use Illuminate\Http\JsonResponse;
 use Illuminate\Http\Request;
@@ -71,4 +72,32 @@ public function statsByItemType(): JsonResponse
 
         return ApiResponse::success($stats, __('message.fetched'));
     }
+
+    /**
+     * 재고 조정 이력 조회
+     */
+    public function adjustments(int $id): JsonResponse
+    {
+        try {
+            $adjustments = $this->service->adjustments($id);
+
+            return ApiResponse::success($adjustments, __('message.fetched'));
+        } catch (\Illuminate\Database\Eloquent\ModelNotFoundException $e) {
+            return ApiResponse::error(__('error.stock.not_found'), 404);
+        }
+    }
+
+    /**
+     * 재고 조정 등록
+     */
+    public function storeAdjustment(int $id, StoreStockAdjustmentRequest $request): JsonResponse
+    {
+        try {
+            $result = $this->service->createAdjustment($id, $request->validated());
+
+            return ApiResponse::success($result, __('message.created'));
+        } catch (\Illuminate\Database\Eloquent\ModelNotFoundException $e) {
+            return ApiResponse::error(__('error.stock.not_found'), 404);
+        }
+    }
 }

app/Http/Requests/V1/Stock/StoreStockAdjustmentRequest.php

@@ -0,0 +1,29 @@
+<?php
+
+namespace App\Http\Requests\V1\Stock;
+
+use Illuminate\Foundation\Http\FormRequest;
+
+class StoreStockAdjustmentRequest extends FormRequest
+{
+    public function authorize(): bool
+    {
+        return true;
+    }
+
+    public function rules(): array
+    {
+        return [
+            'quantity' => ['required', 'numeric', 'not_in:0'],
+            'remark' => ['nullable', 'string', 'max:500'],
+        ];
+    }
+
+    public function messages(): array
+    {
+        return [
+            'quantity.required' => __('error.stock.adjustment_qty_required'),
+            'quantity.not_in' => __('error.stock.adjustment_qty_zero'),
+        ];
+    }
+}