feat: 第四阶段财务与人事薪资模块

- 新增2个migration(11张表): finance(6表)/hr(5表)
- 新增11个Model + 11个Controller
- 新增50条API路由(总计262条)
- 新增2个前端API模块 + 10个管理页面
- 迁移运行通过, vite build验证通过

backend/app/Models/Finance/FinanceCategory.php

@@ -0,0 +1,37 @@
+<?php
+
+namespace App\Models\Finance;
+
+use App\Traits\BelongsToStore;
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\BelongsTo;
+use Illuminate\Database\Eloquent\Relations\HasMany;
+
+class FinanceCategory extends Model
+{
+    use BelongsToStore;
+
+    protected $fillable = [
+        'store_id', 'parent_id', 'name', 'type', 'level', 'sort', 'status',
+    ];
+
+    protected function casts(): array
+    {
+        return [
+            'type' => 'integer',
+            'level' => 'integer',
+            'sort' => 'integer',
+            'status' => 'integer',
+        ];
+    }
+
+    public function children(): HasMany
+    {
+        return $this->hasMany(self::class, 'parent_id');
+    }
+
+    public function parent(): BelongsTo
+    {
+        return $this->belongsTo(self::class, 'parent_id');
+    }
+}