feat(telegram): 订阅/下载补齐 year/rating/genres/原名/语言 富通知字段

- 模型: Subscription/DownloadTask 新增 OriginalName/OriginalLanguage/Year/
  Rating/Genres 列(GORM AutoMigrate 自动建列, 无需手写迁移)
- enrich 链路: displayMetadata 与 DownloadTaskMeta 携带新字段, 从
  SearchExternalMedia(TMDb/豆瓣/Bangumi)结果回填并持久化; 放宽提前返回
  门槛, 已有海报但缺新字段时仍补齐
- 通知: 订阅/下载完成事件 data 注入 year/rating/genres/original_title/
  original_language, 喂给作者富模板 formatTelegramMediaNotification
- 测试: 新增端到端断言, 验证补齐字段透传进 Telegram caption

internal/service/downloads.go

@@ -110,6 +110,11 @@ type DownloadTaskMeta struct {
 	MediaType            string
 	MediaCategory        string
 	SourceCategory       string
+	OriginalName         string
+	OriginalLanguage     string
+	Year                 int
+	Rating               float32
+	Genres               string
 	AllowExistingLibrary bool
 }
 
@@ -570,6 +575,11 @@ func (d *DownloadService) createTask(ctx context.Context, userID, urlStr, savePa
 		SavePath:             savePath,
 		MediaType:            meta.MediaType,
 		MediaCategory:        meta.MediaCategory,
+		OriginalName:         meta.OriginalName,
+		OriginalLanguage:     meta.OriginalLanguage,
+		Year:                 meta.Year,
+		Rating:               meta.Rating,
+		Genres:               meta.Genres,
 		Status:               "queued",
 		AllowExistingLibrary: meta.AllowExistingLibrary,
 	}
@@ -1381,6 +1391,21 @@ func (d *DownloadService) notifyDownloadComplete(ctx context.Context, torrent QB
 		if strings.TrimSpace(task.Overview) != "" {
 			data["overview"] = task.Overview
 		}
+		if strings.TrimSpace(task.OriginalName) != "" {
+			data["original_title"] = task.OriginalName
+		}
+		if strings.TrimSpace(task.OriginalLanguage) != "" {
+			data["original_language"] = task.OriginalLanguage
+		}
+		if task.Year > 0 {
+			data["year"] = task.Year
+		}
+		if task.Rating > 0 {
+			data["rating"] = task.Rating
+		}
+		if strings.TrimSpace(task.Genres) != "" {
+			data["genres"] = task.Genres
+		}
 	}
 	go func() {
 		ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)