feat: delete old file when updating version with new file

If file_path is different from existing file, remove the old file

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

backend/internal/router/admin/versions.go

@@ -453,6 +453,18 @@ func handleUpdateVersionGlobal(c *gin.Context) {
 
 	log.Printf("[DEBUG] Updates map: %+v\n", updates)
 
+	// 如果文件被更新，删除旧文件
+	if req.FilePath != "" && req.FilePath != version.FilePath {
+		oldFilePath := filepath.Join(".", version.FilePath)
+		if _, err := os.Stat(oldFilePath); err == nil {
+			if err := os.Remove(oldFilePath); err != nil {
+				log.Printf("[WARN] Failed to remove old file %s: %v\n", oldFilePath, err)
+			} else {
+				log.Printf("[INFO] Removed old file: %s\n", oldFilePath)
+			}
+		}
+	}
+
 	if len(updates) == 0 {
 		response.Success(c, nil)
 		return