渠道: Base URL 智能识别前缀/完整端点 + API 格式垂直堆叠

- upstreamURL 按内容智能拼接: 完整端点直接用 / 含 /v1 只拼资源路径 / 纯域名拼全路径
- resolveBaseURL 不再去 /v1, 交网关识别
- 渠道表 API 格式改垂直堆叠, 显示短标识 chat/completions / responses / messages
- 前端 Base URL 提示支持前缀或完整端点

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

web/src/lib/protocol.ts

@@ -5,6 +5,17 @@ export const PROTOCOL_NAMES: Record<string, string> = {
   messages: 'Anthropic Messages',
 }
 
+// 渠道表格用的短标识
+export const PROTOCOL_SHORT: Record<string, string> = {
+  chat: 'chat/completions',
+  responses: 'responses',
+  messages: 'messages',
+}
+
+export function protocolShort(p: string): string {
+  return PROTOCOL_SHORT[p] ?? p
+}
+
 export const PROTOCOL_OPTIONS: { value: string; label: string }[] = [
   { value: 'chat', label: 'OpenAI Chat Completions' },
   { value: 'responses', label: 'OpenAI Responses API' },