Merge branch 'main' into test

冲突解决：
- wire_gen.go: 合并 antigravityGatewayService 和 ProvideConcurrencyCache
- user_repo_integration_test.go: 保留 NotFound 测试
- antigravity_gateway_service.go: 适配 httpUpstream.Do 新签名

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/internal/service/openai_gateway_service.go

@@ -371,7 +371,7 @@ func (s *OpenAIGatewayService) buildUpstreamRequest(ctx context.Context, c *gin.
 		// API Key accounts use Platform API or custom base URL
 		baseURL := account.GetOpenAIBaseURL()
 		if baseURL != "" {
-			targetURL = baseURL + "/v1/responses"
+			targetURL = baseURL + "/responses"
 		} else {
 			targetURL = openaiPlatformAPIURL
 		}