feat: [HR/기타] 캘린더/배차/설비/재고 + DB 마이그레이션

- 캘린더 CRUD API, 배차차량 관리 API (CRUD + options)
- 배차정보 다중 행 시스템 (shipment_vehicle_dispatches)
- 설비 다중점검주기 + 부 담당자 스키마 추가
- TodayIssue 날짜 기반 조회, Stock/Client 날짜 필터
- i18n 메시지 추가

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/Models/Tenants/Shipment.php

@@ -134,6 +134,14 @@ public function items(): HasMany
         return $this->hasMany(ShipmentItem::class)->orderBy('seq');
     }
 
+    /**
+     * 배차정보 관계
+     */
+    public function vehicleDispatches(): HasMany
+    {
+        return $this->hasMany(ShipmentVehicleDispatch::class)->orderBy('seq');
+    }
+
     /**
      * 거래처 관계
      */

app/Models/Tenants/ShipmentVehicleDispatch.php

@@ -0,0 +1,52 @@
+<?php
+
+namespace App\Models\Tenants;
+
+use App\Traits\Auditable;
+use App\Traits\BelongsToTenant;
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\BelongsTo;
+use Illuminate\Database\Eloquent\SoftDeletes;
+
+class ShipmentVehicleDispatch extends Model
+{
+    use Auditable, BelongsToTenant, SoftDeletes;
+
+    protected $fillable = [
+        'tenant_id',
+        'shipment_id',
+        'seq',
+        'logistics_company',
+        'arrival_datetime',
+        'tonnage',
+        'vehicle_no',
+        'driver_contact',
+        'remarks',
+        'options',
+    ];
+
+    protected $casts = [
+        'seq' => 'integer',
+        'shipment_id' => 'integer',
+        'arrival_datetime' => 'datetime',
+        'options' => 'array',
+    ];
+
+    /**
+     * 출하 관계
+     */
+    public function shipment(): BelongsTo
+    {
+        return $this->belongsTo(Shipment::class);
+    }
+
+    /**
+     * 다음 순번 가져오기
+     */
+    public static function getNextSeq(int $shipmentId): int
+    {
+        $maxSeq = static::where('shipment_id', $shipmentId)->max('seq');
+
+        return ($maxSeq ?? 0) + 1;
+    }
+}