refactor: replace standard log with zap logger and optimize code patterns

- Migrate all log.Printf/log.Println calls to structured zap logging
- Use cmp.Or for cleaner default value handling
- Replace manual loops with slices.ContainsFunc/IndexFunc
- Add batch query methods (IsLikedBatch, IsFavoritedBatch) to solve N+1 problem
- Update JSON tags from omitempty to omitzero for numeric fields
- Use errgroup-style wg.Go for worker goroutines
- Remove duplicate casbin/v2 dependency (keeping v3)
- Add plans/ to gitignore

internal/service/sensitive_service.go

@@ -4,7 +4,6 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
-	"log"
 	"regexp"
 	"strings"
 	"sync"
@@ -14,6 +13,7 @@ import (
 	"carrot_bbs/internal/model"
 	redisclient "carrot_bbs/internal/pkg/redis"
 
+	"go.uber.org/zap"
 	"gorm.io/gorm"
 )
 
@@ -289,13 +289,17 @@ func NewSensitiveService(db *gorm.DB, redisClient *redisclient.Client, config *S
 	// 初始化加载敏感词
 	if config.LoadFromDB {
 		if err := s.loadFromDB(context.Background()); err != nil {
-			log.Printf("Failed to load sensitive words from database: %v", err)
+			zap.L().Warn("Failed to load sensitive words from database",
+				zap.Error(err),
+			)
 		}
 	}
 
 	if config.LoadFromRedis && redisClient != nil {
 		if err := s.loadFromRedis(context.Background()); err != nil {
-			log.Printf("Failed to load sensitive words from redis: %v", err)
+			zap.L().Warn("Failed to load sensitive words from redis",
+				zap.Error(err),
+			)
 		}
 	}
 
@@ -365,7 +369,9 @@ func (s *sensitiveServiceImpl) AddWord(ctx context.Context, word string, categor
 		result := s.db.Where("word = ?", word).First(&existing)
 		if result.Error == gorm.ErrRecordNotFound {
 			if err := s.db.Create(&sensitiveWord).Error; err != nil {
-				log.Printf("Failed to save sensitive word to database: %v", err)
+				zap.L().Warn("Failed to save sensitive word to database",
+					zap.Error(err),
+				)
 			}
 		} else if result.Error == nil {
 			// 更新已存在的记录
@@ -373,7 +379,9 @@ func (s *sensitiveServiceImpl) AddWord(ctx context.Context, word string, categor
 			existing.Level = wordLevel
 			existing.IsActive = true
 			if err := s.db.Save(&existing).Error; err != nil {
-				log.Printf("Failed to update sensitive word in database: %v", err)
+				zap.L().Warn("Failed to update sensitive word in database",
+					zap.Error(err),
+				)
 			}
 		}
 	}
@@ -406,7 +414,9 @@ func (s *sensitiveServiceImpl) RemoveWord(ctx context.Context, word string) erro
 	if s.db != nil {
 		result := s.db.Model(&model.SensitiveWord{}).Where("word = ?", word).Update("is_active", false)
 		if result.Error != nil {
-			log.Printf("Failed to deactivate sensitive word in database: %v", result.Error)
+			zap.L().Warn("Failed to deactivate sensitive word in database",
+				zap.Error(result.Error),
+			)
 		}
 	}
 
@@ -461,7 +471,9 @@ func (s *sensitiveServiceImpl) loadFromDB(ctx context.Context) error {
 		s.tree.AddWord(word.Word, word.Level, word.Category)
 	}
 
-	log.Printf("Loaded %d sensitive words from database", len(words))
+	zap.L().Info("Loaded sensitive words from database",
+		zap.Int("count", len(words)),
+	)
 	return nil
 }