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.

common/limiter/limiter.go

@@ -5,7 +5,7 @@ import (
 	_ "embed"
 	"fmt"
 	"github.com/go-redis/redis/v8"
-	"one-api/common"
+	"one-api/logger"
 	"sync"
 )
 
@@ -27,7 +27,7 @@ func New(ctx context.Context, r *redis.Client) *RedisLimiter {
 		// 预加载脚本
 		limitSHA, err := r.ScriptLoad(ctx, rateLimitScript).Result()
 		if err != nil {
-			common.SysLog(fmt.Sprintf("Failed to load rate limit script: %v", err))
+			logger.SysLog(fmt.Sprintf("Failed to load rate limit script: %v", err))
 		}
 		instance = &RedisLimiter{
 			client:         r,