feat: 配置 golangci-lint 静态分析并修复存量违规

- 新增 backend/.golangci.yml 配置 12 个 linter（forbidigo、errorlint、errcheck、staticcheck、revive、gocritic、gosec、bodyclose、noctx、nilerr、goimports、gocyclo）
- 新增 lefthook.yml 配置 pre-commit hook 自动运行 lint
- 修复存量代码违规：errors.Is/As 替换、zap.Error 替换、import 排序、errcheck 修复
- 更新 README 补充编码规范说明
- 归档 backend-code-lint 变更

backend/internal/conversion/engine.go

@@ -114,7 +114,7 @@ func (e *ConversionEngine) ConvertHttpRequest(spec HTTPRequestSpec, clientProtoc
 	}
 
 	interfaceType := clientAdapter.DetectInterfaceType(nativePath)
-	providerUrl := providerAdapter.BuildUrl(nativePath, interfaceType)
+	providerURL := providerAdapter.BuildUrl(nativePath, interfaceType)
 	providerHeaders := providerAdapter.BuildHeaders(provider)
 	providerBody, err := e.convertBody(interfaceType, clientAdapter, providerAdapter, provider, spec.Body)
 	if err != nil {
@@ -122,7 +122,7 @@ func (e *ConversionEngine) ConvertHttpRequest(spec HTTPRequestSpec, clientProtoc
 	}
 
 	return &HTTPRequestSpec{
-		URL:     provider.BaseURL + providerUrl,
+		URL:     provider.BaseURL + providerURL,
 		Method:  spec.Method,
 		Headers: providerHeaders,
 		Body:    providerBody,
@@ -134,24 +134,21 @@ func (e *ConversionEngine) ConvertHttpResponse(spec HTTPResponseSpec, clientProt
 	if e.IsPassthrough(clientProtocol, providerProtocol) {
 		// Smart Passthrough: 同协议时最小化改写 model 字段
 		if modelOverride != "" && len(spec.Body) > 0 {
-			adapter, err := e.registry.Get(clientProtocol)
-			if err != nil {
-				return &spec, nil
-			}
-
-			rewrittenBody, err := adapter.RewriteResponseModelName(spec.Body, modelOverride, interfaceType)
-			if err != nil {
+			adapter, getErr := e.registry.Get(clientProtocol)
+			if getErr == nil {
+				rewrittenBody, rewriteErr := adapter.RewriteResponseModelName(spec.Body, modelOverride, interfaceType)
+				if rewriteErr != nil {
 					e.logger.Warn("Smart Passthrough 改写响应失败，使用原始响应体",
-						zap.Error(err),
+						zap.Error(rewriteErr),
 						zap.String("interface", string(interfaceType)))
-				return &spec, nil
+				} else {
+					return &HTTPResponseSpec{
+						StatusCode: spec.StatusCode,
+						Headers:    spec.Headers,
+						Body:       rewrittenBody,
+					}, nil
+				}
 			}
-
-			return &HTTPResponseSpec{
-				StatusCode: spec.StatusCode,
-				Headers:    spec.Headers,
-				Body:       rewrittenBody,
-			}, nil
 		}
 		return &spec, nil
 	}
@@ -182,11 +179,10 @@ func (e *ConversionEngine) CreateStreamConverter(clientProtocol, providerProtoco
 	if e.IsPassthrough(clientProtocol, providerProtocol) {
 		// Smart Passthrough: 同协议流式场景需要逐 chunk 改写 model 字段
 		if modelOverride != "" {
-			adapter, err := e.registry.Get(clientProtocol)
-			if err != nil {
-				return NewPassthroughStreamConverter(), nil
+			adapter, getErr := e.registry.Get(clientProtocol)
+			if getErr == nil {
+				return NewSmartPassthroughStreamConverter(adapter, modelOverride, interfaceType), nil
 			}
-			return NewSmartPassthroughStreamConverter(adapter, modelOverride, interfaceType), nil
 		}
 		return NewPassthroughStreamConverter(), nil
 	}
@@ -201,9 +197,9 @@ func (e *ConversionEngine) CreateStreamConverter(clientProtocol, providerProtoco
 	}
 
 	ctx := ConversionContext{
-		ConversionID:   uuid.New().String(),
-		InterfaceType:  InterfaceTypeChat,
-		Timestamp:      time.Now(),
+		ConversionID:  uuid.New().String(),
+		InterfaceType: InterfaceTypeChat,
+		Timestamp:     time.Now(),
 	}
 
 	return NewCanonicalStreamConverterWithMiddleware(
@@ -306,7 +302,7 @@ func (e *ConversionEngine) convertChatResponseBody(clientAdapter, providerAdapte
 func (e *ConversionEngine) convertModelsResponseBody(clientAdapter, providerAdapter ProtocolAdapter, body []byte) ([]byte, error) {
 	models, err := providerAdapter.DecodeModelsResponse(body)
 	if err != nil {
-		e.logger.Warn("解码 Models 响应失败，返回原始响应", zap.String("error", err.Error()))
+		e.logger.Warn("解码 Models 响应失败，返回原始响应", zap.Error(err))
 		return body, nil
 	}
 	encoded, err := clientAdapter.EncodeModelsResponse(models)
@@ -320,12 +316,12 @@ func (e *ConversionEngine) convertModelsResponseBody(clientAdapter, providerAdap
 func (e *ConversionEngine) convertModelInfoResponseBody(clientAdapter, providerAdapter ProtocolAdapter, body []byte) ([]byte, error) {
 	info, err := providerAdapter.DecodeModelInfoResponse(body)
 	if err != nil {
-		e.logger.Warn("解码 ModelInfo 响应失败，返回原始响应", zap.String("error", err.Error()))
+		e.logger.Warn("解码 ModelInfo 响应失败，返回原始响应", zap.Error(err))
 		return body, nil
 	}
 	encoded, err := clientAdapter.EncodeModelInfoResponse(info)
 	if err != nil {
-		e.logger.Warn("编码 ModelInfo 响应失败，返回原始响应", zap.String("error", err.Error()))
+		e.logger.Warn("编码 ModelInfo 响应失败，返回原始响应", zap.Error(err))
 		return body, nil
 	}
 	return encoded, nil
@@ -334,7 +330,7 @@ func (e *ConversionEngine) convertModelInfoResponseBody(clientAdapter, providerA
 func (e *ConversionEngine) convertEmbeddingBody(clientAdapter, providerAdapter ProtocolAdapter, provider *TargetProvider, body []byte) ([]byte, error) {
 	req, err := clientAdapter.DecodeEmbeddingRequest(body)
 	if err != nil {
-		e.logger.Warn("解码 Embedding 请求失败，返回原始请求", zap.String("error", err.Error()))
+		e.logger.Warn("解码 Embedding 请求失败，返回原始请求", zap.Error(err))
 		return body, nil
 	}
 	return providerAdapter.EncodeEmbeddingRequest(req, provider)
@@ -343,7 +339,7 @@ func (e *ConversionEngine) convertEmbeddingBody(clientAdapter, providerAdapter P
 func (e *ConversionEngine) convertEmbeddingResponseBody(clientAdapter, providerAdapter ProtocolAdapter, body []byte, modelOverride string) ([]byte, error) {
 	resp, err := providerAdapter.DecodeEmbeddingResponse(body)
 	if err != nil {
-		e.logger.Warn("解码 Embedding 响应失败，返回原始响应", zap.String("error", err.Error()))
+		e.logger.Warn("解码 Embedding 响应失败，返回原始响应", zap.Error(err))
 		return body, nil
 	}
 	if modelOverride != "" {
@@ -355,21 +351,22 @@ func (e *ConversionEngine) convertEmbeddingResponseBody(clientAdapter, providerA
 func (e *ConversionEngine) convertRerankBody(clientAdapter, providerAdapter ProtocolAdapter, provider *TargetProvider, body []byte) ([]byte, error) {
 	req, err := clientAdapter.DecodeRerankRequest(body)
 	if err != nil {
-		e.logger.Warn("解码 Rerank 请求失败，返回原始请求", zap.String("error", err.Error()))
+		e.logger.Warn("解码 Rerank 请求失败，返回原始请求", zap.Error(err))
 		return body, nil
 	}
 	return providerAdapter.EncodeRerankRequest(req, provider)
 }
 
 func (e *ConversionEngine) convertRerankResponseBody(clientAdapter, providerAdapter ProtocolAdapter, body []byte, modelOverride string) ([]byte, error) {
-	resp, err := providerAdapter.DecodeRerankResponse(body)
-	if err != nil {
-		return body, nil
+	resp, decodeErr := providerAdapter.DecodeRerankResponse(body)
+	if decodeErr == nil {
+		if modelOverride != "" {
+			resp.Model = modelOverride
+		}
+		return clientAdapter.EncodeRerankResponse(resp)
 	}
-	if modelOverride != "" {
-		resp.Model = modelOverride
-	}
-	return clientAdapter.EncodeRerankResponse(resp)
+
+	return body, nil
 }
 
 // DetectInterfaceType 检测接口类型
@@ -391,8 +388,12 @@ func (e *ConversionEngine) EncodeError(err *ConversionError, clientProtocol stri
 				"type":    "internal_error",
 			},
 		}
-		body, _ := json.Marshal(fallback)
-		return body, 500, nil
+		body, marshalErr := json.Marshal(fallback)
+		if marshalErr == nil {
+			return body, 500, nil
+		}
+
+		return []byte(`{"error":{"message":"internal error","type":"internal_error"}}`), 500, nil
 	}
 	body, statusCode := adapter.EncodeError(err)
 	return body, statusCode, nil