refactor: cleanup unused code and simplify internal packages

This commit performs a significant cleanup of the codebase by removing unused functions, methods, and entire files across various internal modules. This reduces technical debt and simplifies the project structure.

Key changes include:
- **cache**: Removed unused cache key generators and metrics snapshots.
- **dto**: Removed redundant converter functions and segment creation helpers.
- **middleware**: Deleted the unused `logger.go` middleware and simplified `ratelimit.go` and `casbin.go`.
- **model**: Removed unused ID helpers, database closing functions, and batch decryption logic.
- **pkg**: Cleaned up unused utility functions in `circuitbreaker`, `crypto`, `cursor`, `hook`, and `utils`.
- **service**: Deleted `account_cleanup_service.go` and removed unused helper functions in `log_cleanup_service.go` and `sensitive_service.go`.
- **repository**: Removed unused private loading methods in `comment_repo.go`.

internal/pkg/tencent/config.go

@@ -46,13 +46,3 @@ type tencentAPIResponse struct {
 	} `json:"Response"`
 }
 
-func ConfigFromAppConfig(cfg *Config) Config {
-	return Config{
-		Enabled:   cfg.Enabled,
-		SecretID:  cfg.SecretID,
-		SecretKey: cfg.SecretKey,
-		Region:    cfg.Region,
-		BizType:   cfg.BizType,
-		Timeout:   cfg.Timeout,
-	}
-}