feat: [calendar] 달력 일정 관리 API 구현

- GET /api/v1/calendar-schedules — 연도별 일정 목록 조회
- GET /api/v1/calendar-schedules/stats — 통계 조회
- GET /api/v1/calendar-schedules/{id} — 단건 조회
- POST /api/v1/calendar-schedules — 등록
- PUT /api/v1/calendar-schedules/{id} — 수정
- DELETE /api/v1/calendar-schedules/{id} — 삭제
- POST /api/v1/calendar-schedules/bulk — 대량 등록

app/Models/Commons/Holiday.php

@@ -0,0 +1,41 @@
+<?php
+
+namespace App\Models\Commons;
+
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\SoftDeletes;
+
+class Holiday extends Model
+{
+    use SoftDeletes;
+
+    protected $table = 'holidays';
+
+    protected $fillable = [
+        'tenant_id',
+        'start_date',
+        'end_date',
+        'name',
+        'type',
+        'is_recurring',
+        'memo',
+        'created_by',
+        'updated_by',
+    ];
+
+    protected $casts = [
+        'start_date' => 'date',
+        'end_date' => 'date',
+        'is_recurring' => 'boolean',
+    ];
+
+    public function scopeForTenant($query, int $tenantId)
+    {
+        return $query->where('tenant_id', $tenantId);
+    }
+
+    public function scopeForYear($query, int $year)
+    {
+        return $query->whereYear('start_date', $year);
+    }
+}