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/Services/StockService.php

@@ -191,6 +191,77 @@ public function show(int $id): Item
             ->findOrFail($id);
     }
 
+    /**
+     * 재고 조정 이력 조회
+     */
+    public function adjustments(int $stockId): array
+    {
+        $tenantId = $this->tenantId();
+
+        $stock = Stock::where('tenant_id', $tenantId)->findOrFail($stockId);
+
+        $transactions = StockTransaction::where('tenant_id', $tenantId)
+            ->where('stock_id', $stock->id)
+            ->where('reason', StockTransaction::REASON_ADJUSTMENT)
+            ->with('creator:id,name')
+            ->orderByDesc('created_at')
+            ->get();
+
+        return $transactions->map(fn ($t) => [
+            'id' => $t->id,
+            'adjusted_at' => $t->created_at->format('Y-m-d H:i'),
+            'quantity' => (float) $t->qty,
+            'balance_qty' => (float) $t->balance_qty,
+            'remark' => $t->remark,
+            'inspector' => $t->creator?->name ?? '-',
+        ])->toArray();
+    }
+
+    /**
+     * 재고 조정 등록
+     */
+    public function createAdjustment(int $stockId, array $data): array
+    {
+        $tenantId = $this->tenantId();
+        $userId = $this->apiUserId();
+
+        return DB::transaction(function () use ($stockId, $data, $tenantId, $userId) {
+            $stock = Stock::where('tenant_id', $tenantId)->findOrFail($stockId);
+
+            $qty = (float) $data['quantity'];
+
+            // 재고량 직접 조정
+            $stock->stock_qty += $qty;
+            $stock->available_qty += $qty;
+            $stock->status = $stock->calculateStatus();
+            $stock->updated_by = $userId;
+            $stock->save();
+
+            // 거래 유형: 양수 → IN, 음수 → OUT
+            $type = $qty >= 0 ? StockTransaction::TYPE_IN : StockTransaction::TYPE_OUT;
+
+            // 거래 이력 기록
+            $this->recordTransaction(
+                stock: $stock,
+                type: $type,
+                qty: $qty,
+                reason: StockTransaction::REASON_ADJUSTMENT,
+                referenceType: 'stock',
+                referenceId: $stock->id,
+                remark: $data['remark'] ?? null
+            );
+
+            return [
+                'id' => $stock->id,
+                'adjusted_at' => now()->format('Y-m-d H:i'),
+                'quantity' => $qty,
+                'balance_qty' => (float) $stock->stock_qty,
+                'remark' => $data['remark'] ?? null,
+                'inspector' => \App\Models\Members\User::find($userId)?->name ?? '-',
+            ];
+        });
+    }
+
     /**
      * 품목코드로 재고 조회 (Item 기준)
      */