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/src/utils/search.ts

@@ -0,0 +1,111 @@
+const CHINESE_CHAR_REGEX = /[\u3400-\u9fff]/u
+
+type PinyinModule = typeof import('pinyin-pro')
+
+let pinyinMod: PinyinModule | null = null
+let pinyinLoading: Promise<void> | null = null
+
+function loadPinyin(): Promise<void> {
+  if (pinyinMod) return Promise.resolve()
+  if (pinyinLoading) return pinyinLoading
+
+  pinyinLoading = import('pinyin-pro')
+    .then((mod) => {
+      pinyinMod = mod
+    })
+    .catch(() => {
+      pinyinLoading = null
+    })
+  return pinyinLoading
+}
+
+export function preloadPinyin(): void {
+  loadPinyin()
+}
+
+function normalizeSearchText(value: string): string {
+  return value.normalize('NFKC').toLocaleLowerCase().replace(/\s+/g, ' ').trim()
+}
+
+function compactSearchText(value: string): string {
+  return normalizeSearchText(value).replace(/\s+/g, '')
+}
+
+function addSearchTerm(terms: Set<string>, value: string): void {
+  const normalizedValue = normalizeSearchText(value)
+  if (!normalizedValue) {
+    return
+  }
+
+  terms.add(normalizedValue)
+
+  const compactValue = normalizedValue.replace(/\s+/g, '')
+  if (compactValue && compactValue !== normalizedValue) {
+    terms.add(compactValue)
+  }
+}
+
+function getPinyinSearchTerms(value: string): string[] {
+  if (!CHINESE_CHAR_REGEX.test(value) || !pinyinMod) {
+    return []
+  }
+
+  const fullPinyin = pinyinMod.pinyin(value, {
+    toneType: 'none',
+    type: 'array',
+  })
+  const initials = pinyinMod.pinyin(value, {
+    pattern: 'first',
+    toneType: 'none',
+    type: 'array',
+  })
+
+  return [
+    fullPinyin.join(' '),
+    fullPinyin.join(''),
+    initials.join(' '),
+    initials.join(''),
+  ]
+}
+
+export function buildSearchTerms(
+  ...values: Array<string | null | undefined>
+): string[] {
+  const terms = new Set<string>()
+
+  for (const rawValue of values) {
+    const value = rawValue?.trim()
+    if (!value) {
+      continue
+    }
+
+    addSearchTerm(terms, value)
+
+    for (const pinyinTerm of getPinyinSearchTerms(value)) {
+      addSearchTerm(terms, pinyinTerm)
+    }
+  }
+
+  return Array.from(terms)
+}
+
+export function matchesSearchQuery(
+  query: string,
+  ...values: Array<string | null | undefined>
+): boolean {
+  const normalizedQuery = normalizeSearchText(query)
+  if (!normalizedQuery) {
+    return true
+  }
+
+  const compactQuery = compactSearchText(normalizedQuery)
+  const queryVariants =
+    compactQuery && compactQuery !== normalizedQuery
+      ? [normalizedQuery, compactQuery]
+      : [normalizedQuery]
+
+  const searchTerms = buildSearchTerms(...values)
+  return searchTerms.some((term) =>
+    queryVariants.some((variant) => term.includes(variant)),
+  )
+}