feat: 为下拉选择组件添加搜索过滤功能，支持拼音匹配

- 新增 search.ts 搜索工具，支持中文拼音（全拼/首字母）模糊匹配
- 新增 select-search-context.ts，通过 provide/inject 为 radix-vue Select 组件注入搜索能力
- MultiSelect、ModelMultiSelect 组件集成搜索框，选项超过阈值时自动显示
- select-content/select-item 组件支持搜索过滤与空状态提示
- StandaloneKeyFormDialog、UserFormDialog 中手写下拉框替换为复用 MultiSelect 组件
- 引入 pinyin-pro 依赖，按需懒加载

Closes #210

Co-authored-by: AoaoMH <kidxb@vip.qq.com>

frontend/package-lock.json

@@ -24,6 +24,7 @@
         "marked": "^16.0.0",
         "otpauth": "^9.5.0",
         "pinia": "^3.0.3",
+        "pinyin-pro": "^3.28.0",
         "radix-vue": "^1.9.17",
         "tailwind-merge": "^3.3.1",
         "three": "^0.180.0",
@@ -4718,6 +4719,12 @@
         }
       }
     },
+    "node_modules/pinyin-pro": {
+      "version": "3.28.0",
+      "resolved": "https://registry.npmmirror.com/pinyin-pro/-/pinyin-pro-3.28.0.tgz",
+      "integrity": "sha512-mMRty6RisoyYNphJrTo3pnvp3w8OMZBrXm9YSWkxhAfxKj1KZk2y8T2PDIZlDDRsvZ0No+Hz6FI4sZpA6Ey25g==",
+      "license": "MIT"
+    },
     "node_modules/pirates": {
       "version": "4.0.7",
       "resolved": "https://registry.npmjs.org/pirates/-/pirates-4.0.7.tgz",