🐛 fix(areas): 修复地区筛选条件默认值问题

- 将level和isDisabled的默认值从空字符串改为'all'
- 调整筛选条件转换逻辑，仅在值不为'all'时才转换为数字
- 更新选择器选项值，将"全部层级"和"全部状态"的value从空字符串改为'all'，确保筛选条件正确传递

src/client/admin/pages/Areas.tsx

@@ -48,9 +48,9 @@ export const AreasPage: React.FC = () => {
   const [page, setPage] = useState(1);
   const [pageSize, setPageSize] = useState(20);
   const [keyword, setKeyword] = useState('');
-  const [level, setLevel] = useState<string>('');
+  const [level, setLevel] = useState<string>('all');
   const [parentId, setParentId] = useState<string>('');
-  const [isDisabled, setIsDisabled] = useState<string>('');
+  const [isDisabled, setIsDisabled] = useState<string>('all');
   const [isCreateDialogOpen, setIsCreateDialogOpen] = useState(false);
   const [isEditDialogOpen, setIsEditDialogOpen] = useState(false);
   const [isDeleteDialogOpen, setIsDeleteDialogOpen] = useState(false);
@@ -62,9 +62,9 @@ export const AreasPage: React.FC = () => {
     page,
     pageSize,
     keyword: keyword || undefined,
-    level: level ? Number(level) : undefined,
+    level: level && level !== 'all' ? Number(level) : undefined,
     parentId: parentId ? Number(parentId) : undefined,
-    isDisabled: isDisabled ? Number(isDisabled) : undefined,
+    isDisabled: isDisabled && isDisabled !== 'all' ? Number(isDisabled) : undefined,
   };
 
   // 查询省市区列表
@@ -272,7 +272,7 @@ export const AreasPage: React.FC = () => {
                   <SelectValue placeholder="选择层级" />
                 </SelectTrigger>
                 <SelectContent>
-                  <SelectItem value="">全部层级</SelectItem>
+                  <SelectItem value="all">全部层级</SelectItem>
                   <SelectItem value="1">省/直辖市</SelectItem>
                   <SelectItem value="2">市</SelectItem>
                   <SelectItem value="3">区/县</SelectItem>
@@ -283,7 +283,7 @@ export const AreasPage: React.FC = () => {
                   <SelectValue placeholder="选择状态" />
                 </SelectTrigger>
                 <SelectContent>
-                  <SelectItem value="">全部状态</SelectItem>
+                  <SelectItem value="all">全部状态</SelectItem>
                   <SelectItem value="0">启用</SelectItem>
                   <SelectItem value="1">禁用</SelectItem>
                 </SelectContent>