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/websocket.go

@@ -15,13 +15,6 @@ import (
 func WssHelper(c *gin.Context, ws *websocket.Conn) (newAPIError *types.NewAPIError) {
 	relayInfo := relaycommon.GenRelayInfoWs(c, ws)
 
-	// get & validate textRequest 获取并验证文本请求
-	//realtimeEvent, err := getAndValidateWssRequest(c, ws)
-	//if err != nil {
-	//	common.LogError(c, fmt.Sprintf("getAndValidateWssRequest failed: %s", err.Error()))
-	//	return service.OpenAIErrorWrapperLocal(err, "invalid_text_request", http.StatusBadRequest)
-	//}
-
 	err := helper.ModelMappedHelper(c, relayInfo, nil)
 	if err != nil {
 		return types.NewError(err, types.ErrorCodeChannelModelMappedError, types.ErrOptionWithSkipRetry())