feat: 第二阶段核心业务模块(CRM/房务/护理/月子餐)

后端:
- 4个迁移文件新增23张业务表
- 23个Eloquent Model(含关联/类型转换/门店隔离)
- 20个Controller(含CRUD+业务操作: 合同审核/入住退房/护理异常处理等)
- 110+条API路由(crm/room/care/meal四大前缀)

前端:
- 4个API模块(crm.js/room.js/care.js/meal.js)
- 13个业务页面(线索/客户/合同/渠道/投诉/房型/房间/预定/护理档案/护理计划/护理记录/菜品/排餐)

backend/app/Models/Care/HealthMetric.php

@@ -0,0 +1,35 @@
+<?php
+
+namespace App\Models\Care;
+
+use App\Models\User;
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\BelongsTo;
+
+class HealthMetric extends Model
+{
+    const UPDATED_AT = null;
+
+    protected $fillable = [
+        'care_profile_id', 'metric_type', 'value', 'unit',
+        'recorded_at', 'recorder_id', 'remark',
+    ];
+
+    protected function casts(): array
+    {
+        return [
+            'value' => 'decimal:2',
+            'recorded_at' => 'datetime',
+        ];
+    }
+
+    public function profile(): BelongsTo
+    {
+        return $this->belongsTo(CareProfile::class, 'care_profile_id');
+    }
+
+    public function recorder(): BelongsTo
+    {
+        return $this->belongsTo(User::class, 'recorder_id');
+    }
+}