feat(web): 申请页改用中文姓名，前端转拼音提交

- ApplyView 的'姓名'字段（2~10 个汉字）替代自定义用户名
- 前端经 pinyin-pro（toneType:none + surname:head 处理姓氏多音字）转拼音作为用户名
- 提交前兜底校验拼音用户名长度（后端规则 [a-z][a-z0-9]{1,31}）
- alert 文案改为实时预览 '通过后自动创建账号 ext_<username>'
- 新增依赖 pinyin-pro@3.29.3

web/package-lock.json

@@ -12,6 +12,7 @@
         "axios": "^1.7.9",
         "element-plus": "^2.9.3",
         "pinia": "^2.3.1",
+        "pinyin-pro": "^3.29.3",
         "vue": "^3.5.13",
         "vue-router": "^4.5.0"
       },
@@ -1830,6 +1831,12 @@
         }
       }
     },
+    "node_modules/pinyin-pro": {
+      "version": "3.29.3",
+      "resolved": "https://registry.npmjs.org/pinyin-pro/-/pinyin-pro-3.29.3.tgz",
+      "integrity": "sha512-+UU9bx6vfDw8amOJGHm0TE0rdQl8VPylsDWviQ5OOQ3e+on1xRP4OqDbiDuMT5OISgvfl/Y6ez1BBRaIP80GLQ==",
+      "license": "MIT"
+    },
     "node_modules/postcss": {
       "version": "8.5.26",
       "resolved": "https://registry.npmjs.org/postcss/-/postcss-8.5.26.tgz",