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/infrastructure.go

@@ -1,7 +1,6 @@
 package wire
 
 import (
-	"log"
 	"time"
 
 	"carrot_bbs/internal/cache"
@@ -62,7 +61,9 @@ func ProvideDB(cfg *config.Config) (*gorm.DB, error) {
 func ProvideRedisClient(cfg *config.Config) *redis.Client {
 	client, err := redis.New(&cfg.Redis)
 	if err != nil {
-		log.Printf("[WARNING] Failed to connect to Redis: %v, falling back to memory cache", err)
+		zap.L().Warn("Failed to connect to Redis, falling back to memory cache",
+			zap.Error(err),
+		)
 		return nil
 	}
 	return client
@@ -85,12 +86,12 @@ func ProvideCache(cfg *config.Config, redisClient *redis.Client) cache.Cache {
 
 	// 直接创建 RedisCache 实例，不依赖全局变量
 	if redisClient == nil {
-		log.Println("[Wire] Warning: Redis client is nil, cache will not be available")
+		zap.L().Warn("Redis client is nil, cache will not be available")
 		return nil
 	}
 
 	cacheInstance := cache.NewRedisCache(redisClient)
-	log.Println("[Wire] Initialized Redis cache via dependency injection")
+	zap.L().Info("Initialized Redis cache via dependency injection")
 	return cacheInstance
 }
 
@@ -128,7 +129,9 @@ func ProvideTransactionManager(db *gorm.DB) repository.TransactionManager {
 func ProvideLogger() *zap.Logger {
 	logger, err := zap.NewProduction()
 	if err != nil {
-		log.Fatalf("Failed to create logger: %v", err)
+		panic("Failed to create logger: " + err.Error())
 	}
+	// 设置为全局 logger，以便在其他地方使用 zap.L()
+	zap.ReplaceGlobals(logger)
 	return logger
 }