refactor: Introduce pre-consume quota and unify relay handlers

This commit introduces a major architectural refactoring to improve quota management, centralize logging, and streamline the relay handling logic.

Key changes:
- **Pre-consume Quota:** Implements a new mechanism to check and reserve user quota *before* making the request to the upstream provider. This ensures more accurate quota deduction and prevents users from exceeding their limits due to concurrent requests.

- **Unified Relay Handlers:** Refactors the relay logic to use generic handlers (e.g., `ChatHandler`, `ImageHandler`) instead of provider-specific implementations. This significantly reduces code duplication and simplifies adding new channels.

- **Centralized Logger:** A new dedicated `logger` package is introduced, and all system logging calls are migrated to use it, moving this responsibility out of the `common` package.

- **Code Reorganization:** DTOs are generalized (e.g., `dalle.go` -> `openai_image.go`) and utility code is moved to more appropriate packages (e.g., `common/http.go` -> `service/http.go`) for better code structure.

relay/channel/xai/text.go

@@ -6,6 +6,7 @@ import (
 	"net/http"
 	"one-api/common"
 	"one-api/dto"
+	"one-api/logger"
 	"one-api/relay/channel/openai"
 	relaycommon "one-api/relay/common"
 	"one-api/relay/helper"
@@ -47,7 +48,7 @@ func xAIStreamHandler(c *gin.Context, info *relaycommon.RelayInfo, resp *http.Re
 		var xAIResp *dto.ChatCompletionsStreamResponse
 		err := json.Unmarshal([]byte(data), &xAIResp)
 		if err != nil {
-			common.SysError("error unmarshalling stream response: " + err.Error())
+			logger.SysError("error unmarshalling stream response: " + err.Error())
 			return true
 		}
 
@@ -63,7 +64,7 @@ func xAIStreamHandler(c *gin.Context, info *relaycommon.RelayInfo, resp *http.Re
 		_ = openai.ProcessStreamResponse(*openaiResponse, &responseTextBuilder, &toolCount)
 		err = helper.ObjectData(c, openaiResponse)
 		if err != nil {
-			common.SysError(err.Error())
+			logger.SysError(err.Error())
 		}
 		return true
 	})
@@ -74,12 +75,12 @@ func xAIStreamHandler(c *gin.Context, info *relaycommon.RelayInfo, resp *http.Re
 	}
 
 	helper.Done(c)
-	common.CloseResponseBodyGracefully(resp)
+	service.CloseResponseBodyGracefully(resp)
 	return usage, nil
 }
 
 func xAIHandler(c *gin.Context, info *relaycommon.RelayInfo, resp *http.Response) (*dto.Usage, *types.NewAPIError) {
-	defer common.CloseResponseBodyGracefully(resp)
+	defer service.CloseResponseBodyGracefully(resp)
 
 	responseBody, err := io.ReadAll(resp.Body)
 	if err != nil {
@@ -101,7 +102,7 @@ func xAIHandler(c *gin.Context, info *relaycommon.RelayInfo, resp *http.Response
 		return nil, types.NewError(err, types.ErrorCodeBadResponseBody)
 	}
 
-	common.IOCopyBytesGracefully(c, resp, encodeJson)
+	service.IOCopyBytesGracefully(c, resp, encodeJson)
 
 	return xaiResponse.Usage, nil
 }