feat: 文章图片上传 JPEG/PNG 自动转 WebP 压缩存储

- JPEG/PNG 上传后自动转为 WebP quality 80 存储，保留原尺寸不 resize
- 仅当 WebP 比原文件小时才采用，否则回退原格式
- GIF/WebP 保持不变直存
- 移除对 common.SaveUploadedFile 的依赖，改用 io.ReadAll + os.WriteFile

internal/controller/post_controller.go

@@ -1,8 +1,14 @@
 package controller
 
 import (
+	"bytes"
 	"errors"
 	"fmt"
+	"image"
+	_ "image/gif"
+	_ "image/jpeg"
+	_ "image/png"
+	"io"
 	"net/http"
 	"os"
 	"path/filepath"
@@ -14,6 +20,7 @@ import (
 	"metazone.cc/metalab/internal/model"
 	"metazone.cc/metalab/internal/service"
 
+	"github.com/chai2010/webp"
 	"github.com/gin-gonic/gin"
 )
 
@@ -358,6 +365,7 @@ var allowedImageExt = map[string]bool{
 }
 
 // UploadImage 上传帖子图片（需登录，multipart/form-data）
+// JPEG/PNG 自动转 WebP quality 80 存储，保留原尺寸不 resize
 func (ctrl *PostController) UploadImage(c *gin.Context) {
 	uid, _, ok := common.GetGinUser(c)
 	if !ok {
@@ -386,6 +394,13 @@ func (ctrl *PostController) UploadImage(c *gin.Context) {
 		return
 	}
 
+	// 读取全部数据（后续 WebP 转换需要）
+	data, err := io.ReadAll(file)
+	if err != nil {
+		common.Error(c, http.StatusInternalServerError, "读取文件失败")
+		return
+	}
+
 	// 存储路径
 	storageDir := "storage/uploads/posts"
 	if err := os.MkdirAll(storageDir, 0755); err != nil {
@@ -393,17 +408,38 @@ func (ctrl *PostController) UploadImage(c *gin.Context) {
 		return
 	}
 
-	// 唯一文件名：uid_timestamp.ext
 	ts := time.Now().UnixMilli()
-	filename := fmt.Sprintf("%d_%d%s", uid, ts, ext)
-	savePath := filepath.Join(storageDir, filename)
+	var savePath, url string
 
-	if err := common.SaveUploadedFile(file, savePath); err != nil {
+	// JPEG/PNG → WebP 压缩存储（保留原尺寸，quality 80）
+	if ext == ".jpg" || ext == ".jpeg" || ext == ".png" {
+		img, _, err := image.Decode(bytes.NewReader(data))
+		if err == nil {
+			var buf bytes.Buffer
+			if err := webp.Encode(&buf, img, &webp.Options{Quality: 80}); err == nil {
+				// 仅当 WebP 比原文件小时才采用，否则回退原格式
+				if buf.Len() > 0 && buf.Len() < len(data) {
+					filename := fmt.Sprintf("%d_%d.webp", uid, ts)
+					savePath = filepath.Join(storageDir, filename)
+					if err := os.WriteFile(savePath, buf.Bytes(), 0644); err == nil {
+						url = "/uploads/posts/" + filename
+					}
+				}
+			}
+		}
+	}
+
+	// 回退：GIF / WebP / 转换失败 / 转换后反而更大 → 原样存储
+	if savePath == "" {
+		filename := fmt.Sprintf("%d_%d%s", uid, ts, ext)
+		savePath = filepath.Join(storageDir, filename)
+		if err := os.WriteFile(savePath, data, 0644); err != nil {
 			common.Error(c, http.StatusInternalServerError, "保存图片失败")
 			return
 		}
+		url = "/uploads/posts/" + filename
+	}
 
-	url := "/uploads/posts/" + filename
 	common.VditorUploadOk(c, map[string]string{header.Filename: url})
 }