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/middleware/casbin.go

@@ -66,23 +66,6 @@ func CasbinAuth(casbinService service.CasbinService) gin.HandlerFunc {
 	}
 }
 
-// OptionalCasbinAuth 可选的 Casbin 权限检查
-// 不阻止请求，但会设置权限标志
-func OptionalCasbinAuth(casbinService service.CasbinService) gin.HandlerFunc {
-	return func(c *gin.Context) {
-		userID, exists := c.Get("user_id")
-		if exists {
-			path := c.Request.URL.Path
-			method := c.Request.Method
-			allowed, err := casbinService.EnforceForUser(c.Request.Context(), userID.(string), path, method)
-			if err == nil {
-				c.Set("permission_granted", allowed)
-			}
-		}
-		c.Next()
-	}
-}
-
 // RequireRole 要求特定角色的中间件
 func RequireRole(casbinService service.CasbinService, requiredRoles ...string) gin.HandlerFunc {
 	return func(c *gin.Context) {

internal/middleware/logger.go

@@ -1,49 +0,0 @@
-package middleware
-
-import (
-	"time"
-
-	"github.com/gin-gonic/gin"
-	"go.uber.org/zap"
-)
-
-// Logger 日志中间件
-func Logger(logger *zap.Logger) gin.HandlerFunc {
-	return func(c *gin.Context) {
-		start := time.Now()
-		path := c.Request.URL.Path
-
-		c.Next()
-
-		latency := time.Since(start)
-		statusCode := c.Writer.Status()
-
-		logger.Info("request",
-			zap.String("method", c.Request.Method),
-			zap.String("path", path),
-			zap.Int("status", statusCode),
-			zap.Duration("latency", latency),
-			zap.String("ip", c.ClientIP()),
-			zap.String("user-agent", c.Request.UserAgent()),
-		)
-	}
-}
-
-// Recovery 恢复中间件
-func Recovery(logger *zap.Logger) gin.HandlerFunc {
-	return func(c *gin.Context) {
-		defer func() {
-			if err := recover(); err != nil {
-				logger.Error("panic recovered",
-					zap.Any("error", err),
-				)
-				c.JSON(500, gin.H{
-					"code":    500,
-					"message": "internal server error",
-				})
-				c.Abort()
-			}
-		}()
-		c.Next()
-	}
-}

internal/middleware/ratelimit.go

@@ -75,27 +75,6 @@ func (rl *RateLimiter) isAllowed(key string) bool {
 	return true
 }
 
-func (rl *RateLimiter) count(key string) int {
-	rl.mu.Lock()
-	defer rl.mu.Unlock()
-
-	now := time.Now()
-	times := rl.requests[key]
-
-	var valid []time.Time
-	for _, t := range times {
-		if now.Sub(t) < rl.window {
-			valid = append(valid, t)
-		}
-	}
-	rl.requests[key] = valid
-	return len(valid)
-}
-
-func RateLimit(requestsPerMinute int) gin.HandlerFunc {
-	return RateLimitWithDuration(requestsPerMinute, time.Minute)
-}
-
 func RateLimitWithDuration(limit int, window time.Duration) gin.HandlerFunc {
 	limiter := NewRateLimiter(limit, window)
 
@@ -115,32 +94,6 @@ func RateLimitWithDuration(limit int, window time.Duration) gin.HandlerFunc {
 	}
 }
 
-func RateLimitWithKey(requestsPerMinute int, keyFunc func(c *gin.Context) string) gin.HandlerFunc {
-	return RateLimitWithDurationAndKey(requestsPerMinute, time.Minute, keyFunc)
-}
-
-func RateLimitWithDurationAndKey(limit int, window time.Duration, keyFunc func(c *gin.Context) string) gin.HandlerFunc {
-	limiter := NewRateLimiter(limit, window)
-
-	return func(c *gin.Context) {
-		key := keyFunc(c)
-		if key == "" {
-			key = c.ClientIP()
-		}
-
-		if !limiter.isAllowed(key) {
-			c.JSON(http.StatusTooManyRequests, gin.H{
-				"code":    429,
-				"message": "too many requests, please try again later",
-			})
-			c.Abort()
-			return
-		}
-
-		c.Next()
-	}
-}
-
 // ============================================================
 // IP 封禁与登录失败追踪
 // ============================================================