feat(labor): 노임관리 API 구현

- Labor 모델 (BelongsToTenant, SoftDeletes)
- LaborController 7개 엔드포인트
- LaborService 비즈니스 로직
- FormRequest 4개 (Index/Store/Update/BulkDelete)
- 마이그레이션 및 라우트 등록

API: GET/POST /labor, GET/PUT/DELETE /labor/{id}, DELETE /labor/bulk, GET /labor/stats

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

app/Models/Labor.php

@@ -0,0 +1,67 @@
+<?php
+
+namespace App\Models;
+
+use App\Traits\BelongsToTenant;
+use App\Traits\ModelTrait;
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\SoftDeletes;
+
+class Labor extends Model
+{
+    use BelongsToTenant, ModelTrait, SoftDeletes;
+
+    protected $table = 'labors';
+
+    protected $fillable = [
+        'tenant_id',
+        'labor_number',
+        'category',
+        'min_m',
+        'max_m',
+        'labor_price',
+        'status',
+        'is_active',
+        'created_by',
+        'updated_by',
+        'deleted_by',
+    ];
+
+    protected $casts = [
+        'min_m' => 'decimal:2',
+        'max_m' => 'decimal:2',
+        'labor_price' => 'integer',
+        'is_active' => 'boolean',
+    ];
+
+    /**
+     * 상태별 필터 Scope
+     */
+    public function scopeByStatus($query, string $status)
+    {
+        return $query->where('status', $status);
+    }
+
+    /**
+     * 구분별 필터 Scope
+     */
+    public function scopeByCategory($query, string $category)
+    {
+        return $query->where('category', $category);
+    }
+
+    /**
+     * 검색 Scope
+     */
+    public function scopeSearch($query, ?string $search)
+    {
+        if (empty($search)) {
+            return $query;
+        }
+
+        return $query->where(function ($q) use ($search) {
+            $q->where('labor_number', 'like', "%{$search}%")
+              ->orWhere('category', 'like', "%{$search}%");
+        });
+    }
+}