refactor: Gitea 式目录改组，移除本分支 SPA 与杂项产物

将 model/service/handler/middleware 迁至 models/services/routers/api/modules/auth，并删除 frontend、embed_static、scripts 及误入库缓存/二进制。

Co-authored-by: Cursor <cursoragent@cursor.com>

services/thumb.go

@@ -0,0 +1,173 @@
+package service
+
+import (
+	"errors"
+	"fmt"
+	"image"
+	"os"
+	"path/filepath"
+	"strings"
+	"sync"
+	"time"
+
+	"golang.org/x/image/draw"
+
+	// 注册解码器
+	_ "image/gif"
+	_ "image/jpeg"
+	_ "image/png"
+
+	_ "golang.org/x/image/webp"
+)
+
+const (
+	// PostThumbMaxSide 正文预览图最长边（像素）
+	PostThumbMaxSide = 1280
+)
+
+var thumbLocks sync.Map // 同一原图并发生成时串行化
+
+// ThumbURLFromUpload 将 /uploads/posts/xxx.webp 转为 /media/thumb/posts/xxx.webp
+func ThumbURLFromUpload(uploadURL string) string {
+	u := strings.TrimSpace(uploadURL)
+	if u == "" {
+		return ""
+	}
+	if strings.HasPrefix(u, "/media/thumb/") {
+		return u
+	}
+	if strings.HasPrefix(u, "/uploads/") {
+		return "/media/thumb/" + strings.TrimPrefix(u, "/uploads/")
+	}
+	return ""
+}
+
+// WarmPostImageThumb 上传后预热缩略图（失败忽略，首次访问仍会生成）
+func WarmPostImageThumb(uploadsRoot, relativePath string) {
+	_, _ = EnsureUploadThumb(uploadsRoot, relativePath)
+}
+
+// EnsureUploadThumb 确保缩略图存在，返回磁盘路径
+// relativePath 形如 posts/1_123.webp（相对 uploads 根目录）
+func EnsureUploadThumb(uploadsRoot, relativePath string) (string, error) {
+	rel, err := sanitizeUploadRel(relativePath)
+	if err != nil {
+		return "", err
+	}
+	// 仅处理帖子正文图
+	if !strings.HasPrefix(rel, "posts/") {
+		return "", errors.New("仅支持帖子图片缩略图")
+	}
+
+	origPath := filepath.Join(uploadsRoot, filepath.FromSlash(rel))
+	if st, err := os.Stat(origPath); err != nil || st.IsDir() {
+		return "", errors.New("原图不存在")
+	}
+
+	thumbPath := filepath.Join(uploadsRoot, ".thumbs", filepath.FromSlash(rel)+".webp")
+	if fresh, err := thumbFresherThan(thumbPath, origPath); err == nil && fresh {
+		return thumbPath, nil
+	}
+
+	lockKey := rel
+	muIface, _ := thumbLocks.LoadOrStore(lockKey, &sync.Mutex{})
+	mu := muIface.(*sync.Mutex)
+	mu.Lock()
+	defer mu.Unlock()
+
+	// 双检
+	if fresh, err := thumbFresherThan(thumbPath, origPath); err == nil && fresh {
+		return thumbPath, nil
+	}
+
+	if err := generateWebPThumb(origPath, thumbPath, PostThumbMaxSide); err != nil {
+		return "", err
+	}
+	return thumbPath, nil
+}
+
+func thumbFresherThan(thumbPath, origPath string) (bool, error) {
+	ts, err := os.Stat(thumbPath)
+	if err != nil {
+		return false, err
+	}
+	os_, err := os.Stat(origPath)
+	if err != nil {
+		return false, err
+	}
+	return !ts.ModTime().Before(os_.ModTime()), nil
+}
+
+func sanitizeUploadRel(relativePath string) (string, error) {
+	rel := strings.TrimSpace(relativePath)
+	rel = strings.TrimPrefix(rel, "/")
+	rel = strings.ReplaceAll(rel, "\\", "/")
+	if rel == "" || strings.Contains(rel, "..") {
+		return "", errors.New("非法路径")
+	}
+	cleaned := filepath.Clean(filepath.FromSlash(rel))
+	if cleaned == "." || strings.HasPrefix(cleaned, "..") {
+		return "", errors.New("非法路径")
+	}
+	return filepath.ToSlash(cleaned), nil
+}
+
+func generateWebPThumb(srcPath, dstPath string, maxSide int) error {
+	f, err := os.Open(srcPath)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	img, _, err := image.Decode(f)
+	if err != nil {
+		return fmt.Errorf("解码图片失败: %w", err)
+	}
+
+	out := resizeToMax(img, maxSide)
+	data, err := encodeWebPBytes(out, ThumbWebPQuality, UploadWebPMethod)
+	if err != nil {
+		return err
+	}
+	if err := os.MkdirAll(filepath.Dir(dstPath), 0755); err != nil {
+		return err
+	}
+
+	tmp := fmt.Sprintf("%s.%d.tmp", dstPath, time.Now().UnixNano())
+	if err := os.WriteFile(tmp, data, 0644); err != nil {
+		return err
+	}
+	if err := os.Rename(tmp, dstPath); err != nil {
+		_ = os.Remove(tmp)
+		return err
+	}
+	return nil
+}
+
+func resizeToMax(src image.Image, maxSide int) image.Image {
+	b := src.Bounds()
+	w, h := b.Dx(), b.Dy()
+	if w <= 0 || h <= 0 {
+		return src
+	}
+	if w <= maxSide && h <= maxSide {
+		return src
+	}
+	var nw, nh int
+	if w >= h {
+		nw = maxSide
+		nh = int(float64(h) * float64(maxSide) / float64(w))
+	} else {
+		nh = maxSide
+		nw = int(float64(w) * float64(maxSide) / float64(h))
+	}
+	if nw < 1 {
+		nw = 1
+	}
+	if nh < 1 {
+		nh = 1
+	}
+	dst := image.NewRGBA(image.Rect(0, 0, nw, nh))
+	draw.CatmullRom.Scale(dst, dst.Bounds(), src, b, draw.Over, nil)
+	return dst
+}