渠道支持多 API 格式 + 协议全名展示

- Channel 新增 formats(jsonb: chat|responses|messages), 一个渠道可同时声明
  支持 OpenAI Chat Completions / OpenAI Responses API / Anthropic Messages
- 路由改为按渠道声明的 formats 决定直通/转换: 客户端协议在 formats 内直通,
  否则转换为其首选支持格式(chat > messages > responses)
- 兼容旧数据: formats 为空时按 provider 推断(openai→chat+responses, anthropic→messages, compatible→chat)
- 前端: 渠道表/表单展示 API 格式(支持多选), usage 明细显示协议全名
  (OpenAI Chat Completions / OpenAI Responses API / Anthropic Messages)

Co-Authored-By: Claude <noreply@anthropic.com>

web/src/lib/protocol.ts

@@ -0,0 +1,16 @@
+// 协议格式显示名与选项
+export const PROTOCOL_NAMES: Record<string, string> = {
+  chat: 'OpenAI Chat Completions',
+  responses: 'OpenAI Responses API',
+  messages: 'Anthropic Messages',
+}
+
+export const PROTOCOL_OPTIONS: { value: string; label: string }[] = [
+  { value: 'chat', label: 'OpenAI Chat Completions' },
+  { value: 'responses', label: 'OpenAI Responses API' },
+  { value: 'messages', label: 'Anthropic Messages' },
+]
+
+export function protocolName(p: string): string {
+  return PROTOCOL_NAMES[p] ?? p
+}