feat: add ads/sponsor/captcha modules and polish home & chat UI

backend/service/upload.go

@@ -7,6 +7,7 @@ import (
 	"encoding/hex"
 	"errors"
 	"image"
+	_ "image/gif"
 	_ "image/jpeg"
 	_ "image/png"
 	"io"
@@ -77,6 +78,9 @@ func (s *UploadService) EnsureDir() error {
 	if err := os.MkdirAll(filepath.Join(s.dir, "backgrounds"), 0o755); err != nil {
 		return err
 	}
+	if err := os.MkdirAll(filepath.Join(s.dir, "ads"), 0o755); err != nil {
+		return err
+	}
 	return os.MkdirAll(filepath.Join(s.dir, "brand"), 0o755)
 }
 
@@ -166,7 +170,10 @@ func detectImageFormat(data []byte) (imageFormat, error) {
 	if len(data) >= 12 && string(data[0:4]) == "RIFF" && string(data[8:12]) == "WEBP" {
 		return imageFormat{ext: ".webp", mime: "image/webp"}, nil
 	}
-	return imageFormat{}, errors.New("仅支持 JPEG / PNG / WebP")
+	if len(data) >= 6 && (string(data[0:6]) == "GIF87a" || string(data[0:6]) == "GIF89a") {
+		return imageFormat{ext: ".gif", mime: "image/gif"}, nil
+	}
+	return imageFormat{}, errors.New("仅支持 JPEG / PNG / WebP / GIF")
 }
 
 func decodeImageSizeReader(r io.Reader, mime string) (w, h int, err error) {
@@ -403,6 +410,91 @@ func (s *UploadService) SaveBackground(src io.Reader) (string, error) {
 	return "/uploads/backgrounds/" + filename, nil
 }
 
+const AdAssetMaxBytes = 2 << 20 // 收款码 / 广告素材 2MB
+
+// SaveAdAsset 保存广告相关图片（收款码等）到 uploads/ads，保留原格式含 GIF
+func (s *UploadService) SaveAdAsset(src io.Reader) (string, error) {
+	if src == nil {
+		return "", errors.New("文件为空")
+	}
+	tooLarge := func() error { return errors.New("图片不能超过 2MB") }
+
+	head := make([]byte, 12)
+	n, err := io.ReadFull(src, head)
+	if err != nil && !errors.Is(err, io.ErrUnexpectedEOF) && !errors.Is(err, io.EOF) {
+		return "", errors.New("读取图片失败")
+	}
+	if n == 0 {
+		return "", errors.New("文件为空")
+	}
+	format, err := detectImageFormat(head[:n])
+	if err != nil {
+		return "", err
+	}
+	if err := os.MkdirAll(filepath.Join(s.dir, "ads"), 0o755); err != nil {
+		return "", err
+	}
+	nameBytes := make([]byte, 16)
+	if _, err := rand.Read(nameBytes); err != nil {
+		return "", err
+	}
+	filename := hex.EncodeToString(nameBytes) + format.ext
+	fullPath := filepath.Join(s.dir, "ads", filename)
+	tmp := fullPath + ".partial"
+	if s.ops != nil {
+		release, e := s.ops.BeginTemporary(tmp)
+		if e != nil {
+			return "", e
+		}
+		defer release()
+	}
+	f, err := os.OpenFile(tmp, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0o644)
+	if err != nil {
+		return "", err
+	}
+	remain := AdAssetMaxBytes + 1 - int64(n)
+	if remain < 0 {
+		_ = f.Close()
+		_ = os.Remove(tmp)
+		return "", tooLarge()
+	}
+	if _, err := f.Write(head[:n]); err != nil {
+		_ = f.Close()
+		_ = os.Remove(tmp)
+		return "", err
+	}
+	writtenRest, copyErr := io.Copy(f, io.LimitReader(src, remain))
+	_ = f.Close()
+	if copyErr != nil {
+		_ = os.Remove(tmp)
+		return "", copyErr
+	}
+	if int64(n)+writtenRest > AdAssetMaxBytes {
+		_ = os.Remove(tmp)
+		return "", tooLarge()
+	}
+	rf, err := os.Open(tmp)
+	if err != nil {
+		_ = os.Remove(tmp)
+		return "", err
+	}
+	w, h, err := decodeImageSizeReader(rf, format.mime)
+	_ = rf.Close()
+	if err != nil {
+		_ = os.Remove(tmp)
+		return "", err
+	}
+	if w < 1 || h < 1 || w > 4096 || h > 4096 {
+		_ = os.Remove(tmp)
+		return "", errors.New("图片尺寸无效")
+	}
+	if err := os.Rename(tmp, fullPath); err != nil {
+		_ = os.Remove(tmp)
+		return "", err
+	}
+	return "/uploads/ads/" + filename, nil
+}
+
 // CopyBackgroundFromMedia 把当前用户媒体库里的一张图复制进 backgrounds，不写站点设置
 func (s *UploadService) CopyBackgroundFromMedia(userID, attachmentID uint) (string, error) {
 	var att model.Attachment