feat: 完善使用记录端点可观测性与分布统计

将入站、上游与路径三类端点分布统一到使用记录页的一致化卡片交互中，并补齐端点元数据与统计链路，提升排障与流量分析效率。

backend/internal/handler/openai_gateway_handler.go

@@ -37,6 +37,13 @@ type OpenAIGatewayHandler struct {
 	cfg                     *config.Config
 }
 
+const (
+	openAIInboundEndpointResponses       = "/v1/responses"
+	openAIInboundEndpointMessages        = "/v1/messages"
+	openAIInboundEndpointChatCompletions = "/v1/chat/completions"
+	openAIUpstreamEndpointResponses      = "/v1/responses"
+)
+
 // NewOpenAIGatewayHandler creates a new OpenAIGatewayHandler
 func NewOpenAIGatewayHandler(
 	gatewayService *service.OpenAIGatewayService,
@@ -362,6 +369,8 @@ func (h *OpenAIGatewayHandler) Responses(c *gin.Context) {
 				User:               apiKey.User,
 				Account:            account,
 				Subscription:       subscription,
+				InboundEndpoint:    normalizedOpenAIInboundEndpoint(c, openAIInboundEndpointResponses),
+				UpstreamEndpoint:   normalizedOpenAIUpstreamEndpoint(c, openAIUpstreamEndpointResponses),
 				UserAgent:          userAgent,
 				IPAddress:          clientIP,
 				RequestPayloadHash: requestPayloadHash,
@@ -738,6 +747,8 @@ func (h *OpenAIGatewayHandler) Messages(c *gin.Context) {
 				User:               apiKey.User,
 				Account:            account,
 				Subscription:       subscription,
+				InboundEndpoint:    normalizedOpenAIInboundEndpoint(c, openAIInboundEndpointMessages),
+				UpstreamEndpoint:   normalizedOpenAIUpstreamEndpoint(c, openAIUpstreamEndpointResponses),
 				UserAgent:          userAgent,
 				IPAddress:          clientIP,
 				RequestPayloadHash: requestPayloadHash,
@@ -1235,6 +1246,8 @@ func (h *OpenAIGatewayHandler) ResponsesWebSocket(c *gin.Context) {
 					User:               apiKey.User,
 					Account:            account,
 					Subscription:       subscription,
+					InboundEndpoint:    normalizedOpenAIInboundEndpoint(c, openAIInboundEndpointResponses),
+					UpstreamEndpoint:   normalizedOpenAIUpstreamEndpoint(c, openAIUpstreamEndpointResponses),
 					UserAgent:          userAgent,
 					IPAddress:          clientIP,
 					RequestPayloadHash: service.HashUsageRequestPayload(firstMessage),
@@ -1530,6 +1543,62 @@ func openAIWSIngressFallbackSessionSeed(userID, apiKeyID int64, groupID *int64)
 	return fmt.Sprintf("openai_ws_ingress:%d:%d:%d", gid, userID, apiKeyID)
 }
 
+func normalizedOpenAIInboundEndpoint(c *gin.Context, fallback string) string {
+	path := strings.TrimSpace(fallback)
+	if c != nil {
+		if fullPath := strings.TrimSpace(c.FullPath()); fullPath != "" {
+			path = fullPath
+		} else if c.Request != nil && c.Request.URL != nil {
+			if requestPath := strings.TrimSpace(c.Request.URL.Path); requestPath != "" {
+				path = requestPath
+			}
+		}
+	}
+
+	switch {
+	case strings.Contains(path, openAIInboundEndpointChatCompletions):
+		return openAIInboundEndpointChatCompletions
+	case strings.Contains(path, openAIInboundEndpointMessages):
+		return openAIInboundEndpointMessages
+	case strings.Contains(path, openAIInboundEndpointResponses):
+		return openAIInboundEndpointResponses
+	default:
+		return path
+	}
+}
+
+func normalizedOpenAIUpstreamEndpoint(c *gin.Context, fallback string) string {
+	base := strings.TrimSpace(fallback)
+	if base == "" {
+		base = openAIUpstreamEndpointResponses
+	}
+	base = strings.TrimRight(base, "/")
+
+	if c == nil || c.Request == nil || c.Request.URL == nil {
+		return base
+	}
+
+	path := strings.TrimRight(strings.TrimSpace(c.Request.URL.Path), "/")
+	if path == "" {
+		return base
+	}
+
+	idx := strings.LastIndex(path, "/responses")
+	if idx < 0 {
+		return base
+	}
+
+	suffix := strings.TrimSpace(path[idx+len("/responses"):])
+	if suffix == "" || suffix == "/" {
+		return base
+	}
+	if !strings.HasPrefix(suffix, "/") {
+		return base
+	}
+
+	return base + suffix
+}
+
 func isOpenAIWSUpgradeRequest(r *http.Request) bool {
 	if r == nil {
 		return false