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/wire/casbin.go

@@ -1,8 +1,6 @@
 package wire
 
 import (
-	"log"
-
 	"carrot_bbs/internal/cache"
 	"carrot_bbs/internal/config"
 	"carrot_bbs/internal/repository"
@@ -11,6 +9,7 @@ import (
 	"github.com/casbin/casbin/v3"
 	gormadapter "github.com/casbin/gorm-adapter/v3"
 	"github.com/google/wire"
+	"go.uber.org/zap"
 	"gorm.io/gorm"
 )
 
@@ -26,21 +25,27 @@ func ProvideCasbinEnforcer(cfg *config.Config, db *gorm.DB) *casbin.Enforcer {
 	// 创建 GORM 适配器，连接数据库
 	adapter, err := gormadapter.NewAdapterByDB(db)
 	if err != nil {
-		log.Fatalf("Failed to create Casbin GORM adapter: %v", err)
+		zap.L().Fatal("Failed to create Casbin GORM adapter",
+			zap.Error(err),
+		)
 	}
 
 	// 创建 Casbin Enforcer，使用数据库适配器
 	enforcer, err := casbin.NewEnforcer(cfg.Casbin.ModelPath, adapter)
 	if err != nil {
-		log.Fatalf("Failed to create Casbin enforcer: %v", err)
+		zap.L().Fatal("Failed to create Casbin enforcer",
+			zap.Error(err),
+		)
 	}
 
 	// 从数据库加载策略
 	if err := enforcer.LoadPolicy(); err != nil {
-		log.Printf("[WARNING] Failed to load Casbin policy: %v", err)
+		zap.L().Warn("Failed to load Casbin policy",
+			zap.Error(err),
+		)
 	}
 
-	log.Println("[Wire] Initialized Casbin enforcer with GORM adapter")
+	zap.L().Info("Initialized Casbin enforcer with GORM adapter")
 	return enforcer
 }