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>

server/internal/api/admin_channels.go

@@ -33,7 +33,8 @@ func (h *Handler) AdminChannels(c *gin.Context) {
 			masked = "****"
 		}
 		out = append(out, gin.H{
-			"id": ch.ID, "name": ch.Name, "provider": ch.Provider, "formats": ch.FormatsEffective(), "base_url": ch.BaseURL,
+			"id": ch.ID, "name": ch.Name, "provider": ch.Provider, "formats": ch.FormatsEffective(),
+			"base_url": ch.BaseURL,
 			"api_key_masked": masked, "weight": ch.Weight, "priority": ch.Priority,
 			"timeout_ms": ch.TimeoutMS, "max_concurrency": ch.MaxConcurrency,
 			"health_status": ch.HealthStatus, "enabled": ch.Enabled,
@@ -47,7 +48,7 @@ type channelBody struct {
 	Name           string   `json:"name" binding:"required,min=1,max=64"`
 	Provider       string   `json:"provider"` // 可选：为空时按 formats 推断（兼容旧数据）
 	Formats        []string `json:"formats"`  // 原生支持的协议 chat|responses|messages（主配置）
-	BaseURL        string   `json:"base_url"` // 可选：为空时按供应商默认（openai/anthropic）
+	BaseURL        string   `json:"base_url"` // 可选：留空按供应商默认；支持前缀或完整端点
 	APIKey         string   `json:"api_key"`
 	Weight         *int     `json:"weight"`
 	Priority       *int     `json:"priority"`
@@ -56,7 +57,7 @@ type channelBody struct {
 	Enabled        *bool    `json:"enabled"`
 }
 
-// resolveBaseURL 渠道 base_url：留空按供应商默认；兼容用户填完整地址（含 /v1）。
+// resolveBaseURL 渠道 base_url：留空按供应商默认；网关按内容智能识别前缀/完整端点。
 func resolveBaseURL(provider, raw string) (string, error) {
 	base := strings.TrimRight(raw, "/")
 	if base == "" {
@@ -70,7 +71,7 @@ func resolveBaseURL(provider, raw string) (string, error) {
 	if base == "" {
 		return "", errors.New("base_url required for compatible channels")
 	}
-	return strings.TrimSuffix(base, "/v1"), nil
+	return base, nil
 }
 
 func validateProvider(p string) bool {

server/internal/proxy/passthrough.go

@@ -15,6 +15,7 @@ import (
 	"time"
 
 	"github.com/gin-gonic/gin"
+	"github.com/openteam/server/internal/channel"
 	"github.com/openteam/server/internal/store"
 )