refactor(global-model): migrate model metadata to flexible config structure

将模型配置从多个固定字段（description, official_url, icon_url, default_supports_* 等）
统一为灵活的 config JSON 字段，提高扩展性。同时优化前端模型创建表单，支持从 models-dev
列表直接选择模型快速填充。

主要变更：
- 后端：模型表迁移，支持 config JSON 存储模型能力和元信息
- 前端：GlobalModelFormDialog 支持两种创建方式（列表选择/手动填写）
- API 类型更新，对齐新的数据结构

frontend/src/api/models-dev.ts

@@ -0,0 +1,244 @@
+/**
+ * Models.dev API 服务
+ * 通过后端代理获取 models.dev 数据（解决跨域问题）
+ */
+
+import api from './client'
+
+// 缓存配置
+const CACHE_KEY = 'models_dev_cache'
+const CACHE_DURATION = 15 * 60 * 1000 // 15 分钟
+
+// Models.dev API 数据结构
+export interface ModelsDevCost {
+  input?: number
+  output?: number
+  reasoning?: number
+  cache_read?: number
+}
+
+export interface ModelsDevLimit {
+  context?: number
+  output?: number
+}
+
+export interface ModelsDevModel {
+  id: string
+  name: string
+  family?: string
+  reasoning?: boolean
+  tool_call?: boolean
+  structured_output?: boolean
+  temperature?: boolean
+  attachment?: boolean
+  knowledge?: string
+  release_date?: string
+  last_updated?: string
+  input?: string[] // 输入模态: text, image, audio, video, pdf
+  output?: string[] // 输出模态: text, image, audio
+  open_weights?: boolean
+  cost?: ModelsDevCost
+  limit?: ModelsDevLimit
+  deprecated?: boolean
+}
+
+export interface ModelsDevProvider {
+  id: string
+  env?: string[]
+  npm?: string
+  api?: string
+  name: string
+  doc?: string
+  models: Record<string, ModelsDevModel>
+}
+
+export type ModelsDevData = Record<string, ModelsDevProvider>
+
+// 扁平化的模型列表项（用于搜索和选择）
+export interface ModelsDevModelItem {
+  providerId: string
+  providerName: string
+  modelId: string
+  modelName: string
+  family?: string
+  inputPrice?: number
+  outputPrice?: number
+  contextLimit?: number
+  outputLimit?: number
+  supportsVision?: boolean
+  supportsToolCall?: boolean
+  supportsReasoning?: boolean
+  deprecated?: boolean
+  // 用于 display_metadata 的额外字段
+  knowledgeCutoff?: string
+  releaseDate?: string
+  inputModalities?: string[]
+  outputModalities?: string[]
+}
+
+interface CacheData {
+  timestamp: number
+  data: ModelsDevData
+}
+
+// 内存缓存
+let memoryCache: CacheData | null = null
+
+/**
+ * 获取 models.dev 数据（带缓存）
+ */
+export async function getModelsDevData(): Promise<ModelsDevData> {
+  // 1. 检查内存缓存
+  if (memoryCache && Date.now() - memoryCache.timestamp < CACHE_DURATION) {
+    return memoryCache.data
+  }
+
+  // 2. 检查 localStorage 缓存
+  try {
+    const cached = localStorage.getItem(CACHE_KEY)
+    if (cached) {
+      const cacheData: CacheData = JSON.parse(cached)
+      if (Date.now() - cacheData.timestamp < CACHE_DURATION) {
+        memoryCache = cacheData
+        return cacheData.data
+      }
+    }
+  } catch {
+    // 缓存解析失败，忽略
+  }
+
+  // 3. 从后端代理获取新数据
+  const response = await api.get<ModelsDevData>('/api/admin/models/external')
+  const data = response.data
+
+  // 4. 更新缓存
+  const cacheData: CacheData = {
+    timestamp: Date.now(),
+    data,
+  }
+  memoryCache = cacheData
+  try {
+    localStorage.setItem(CACHE_KEY, JSON.stringify(cacheData))
+  } catch {
+    // localStorage 写入失败，忽略
+  }
+
+  return data
+}
+
+/**
+ * 获取扁平化的模型列表
+ */
+export async function getModelsDevList(): Promise<ModelsDevModelItem[]> {
+  const data = await getModelsDevData()
+  const items: ModelsDevModelItem[] = []
+
+  for (const [providerId, provider] of Object.entries(data)) {
+    if (!provider.models) continue
+
+    for (const [modelId, model] of Object.entries(provider.models)) {
+      items.push({
+        providerId,
+        providerName: provider.name,
+        modelId,
+        modelName: model.name || modelId,
+        family: model.family,
+        inputPrice: model.cost?.input,
+        outputPrice: model.cost?.output,
+        contextLimit: model.limit?.context,
+        outputLimit: model.limit?.output,
+        supportsVision: model.input?.includes('image'),
+        supportsToolCall: model.tool_call,
+        supportsReasoning: model.reasoning,
+        deprecated: model.deprecated,
+        // display_metadata 相关字段
+        knowledgeCutoff: model.knowledge,
+        releaseDate: model.release_date,
+        inputModalities: model.input,
+        outputModalities: model.output,
+      })
+    }
+  }
+
+  // 按 provider 名称和模型名称排序
+  items.sort((a, b) => {
+    const providerCompare = a.providerName.localeCompare(b.providerName)
+    if (providerCompare !== 0) return providerCompare
+    return a.modelName.localeCompare(b.modelName)
+  })
+
+  return items
+}
+
+/**
+ * 搜索模型
+ */
+export async function searchModelsDevModels(
+  query: string,
+  options?: {
+    limit?: number
+    excludeDeprecated?: boolean
+  }
+): Promise<ModelsDevModelItem[]> {
+  const allModels = await getModelsDevList()
+  const { limit = 50, excludeDeprecated = true } = options || {}
+
+  const queryLower = query.toLowerCase()
+
+  const filtered = allModels.filter((model) => {
+    if (excludeDeprecated && model.deprecated) return false
+
+    // 搜索模型 ID、名称、provider 名称、family
+    return (
+      model.modelId.toLowerCase().includes(queryLower) ||
+      model.modelName.toLowerCase().includes(queryLower) ||
+      model.providerName.toLowerCase().includes(queryLower) ||
+      model.family?.toLowerCase().includes(queryLower)
+    )
+  })
+
+  // 排序：精确匹配优先
+  filtered.sort((a, b) => {
+    const aExact =
+      a.modelId.toLowerCase() === queryLower ||
+      a.modelName.toLowerCase() === queryLower
+    const bExact =
+      b.modelId.toLowerCase() === queryLower ||
+      b.modelName.toLowerCase() === queryLower
+    if (aExact && !bExact) return -1
+    if (!aExact && bExact) return 1
+    return 0
+  })
+
+  return filtered.slice(0, limit)
+}
+
+/**
+ * 获取特定模型详情
+ */
+export async function getModelsDevModel(
+  providerId: string,
+  modelId: string
+): Promise<ModelsDevModel | null> {
+  const data = await getModelsDevData()
+  return data[providerId]?.models?.[modelId] || null
+}
+
+/**
+ * 获取 provider logo URL
+ */
+export function getProviderLogoUrl(providerId: string): string {
+  return `https://models.dev/logos/${providerId}.svg`
+}
+
+/**
+ * 清除缓存
+ */
+export function clearModelsDevCache(): void {
+  memoryCache = null
+  try {
+    localStorage.removeItem(CACHE_KEY)
+  } catch {
+    // 忽略错误
+  }
+}