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/upload_service.go

@@ -2,6 +2,7 @@ package service
 
 import (
 	"bytes"
+	"cmp"
 	"context"
 	"crypto/sha256"
 	"fmt"
@@ -9,7 +10,6 @@ import (
 	"image/jpeg"
 	"image/png"
 	"io"
-	"log"
 	"mime"
 	"mime/multipart"
 	"net/http"
@@ -17,7 +17,9 @@ import (
 	"strings"
 
 	"carrot_bbs/internal/pkg/s3"
+
 	"github.com/disintegration/imaging"
+	"go.uber.org/zap"
 
 	_ "golang.org/x/image/bmp"
 	_ "golang.org/x/image/tiff"
@@ -65,7 +67,9 @@ func (s *UploadService) UploadImage(ctx context.Context, file *multipart.FileHea
 	// 生成预览图
 	previewURL, previewURLLarge, err := s.GeneratePreviewImages(ctx, processedData, hashStr)
 	if err != nil {
-		log.Printf("[WARN] Failed to generate preview images: %v", err)
+		zap.L().Warn("Failed to generate preview images",
+			zap.Error(err),
+		)
 	}
 
 	return url, previewURL, previewURLLarge, nil
@@ -189,10 +193,7 @@ func prepareImageForUpload(file *multipart.FileHeader) ([]byte, string, string,
 	// 优先从文件字节探测真实类型，避免前端压缩/转码后 header 与实际格式不一致
 	detectedType := normalizeImageContentType(http.DetectContentType(originalData))
 	headerType := normalizeImageContentType(file.Header.Get("Content-Type"))
-	contentType := detectedType
-	if contentType == "" || contentType == "application/octet-stream" {
-		contentType = headerType
-	}
+	contentType := cmp.Or(detectedType, headerType, "application/octet-stream")
 
 	compressedData, compressedType, err := compressImageData(originalData, contentType)
 	if err != nil {
@@ -201,21 +202,9 @@ func prepareImageForUpload(file *multipart.FileHeader) ([]byte, string, string,
 		compressedType = contentType
 	}
 
-	if compressedType == "" {
-		compressedType = contentType
-	}
-	if compressedType == "" {
-		compressedType = http.DetectContentType(compressedData)
-	}
+	compressedType = cmp.Or(compressedType, http.DetectContentType(compressedData))
 
-	ext := getExtFromContentType(compressedType)
-	if ext == "" {
-		ext = strings.ToLower(filepath.Ext(file.Filename))
-	}
-	if ext == "" {
-		// 最终兜底，避免对象名无扩展名导致 URL 语义不明确
-		ext = ".jpg"
-	}
+	ext := cmp.Or(getExtFromContentType(compressedType), strings.ToLower(filepath.Ext(file.Filename)), ".jpg")
 
 	return compressedData, compressedType, ext, nil
 }
@@ -302,13 +291,17 @@ func (s *UploadService) GeneratePreviewImages(ctx context.Context, originalData
 	// 生成普通预览图（列表/网格模式）
 	previewURL, err = s.generatePreview(ctx, img, originalWidth, originalHeight, "preview", PreviewMaxWidth, hash)
 	if err != nil {
-		log.Printf("[WARN] Failed to generate preview: %v", err)
+		zap.L().Warn("Failed to generate preview",
+			zap.Error(err),
+		)
 	}
 
 	// 生成大预览图（详情页）
 	previewURLLarge, err = s.generatePreview(ctx, img, originalWidth, originalHeight, "large", PreviewMaxHeight, hash)
 	if err != nil {
-		log.Printf("[WARN] Failed to generate large preview: %v", err)
+		zap.L().Warn("Failed to generate large preview",
+			zap.Error(err),
+		)
 	}
 
 	return previewURL, previewURLLarge, nil