refactor(tiptap): export isValidUrl and UploadImageNodeView for testability

libs/tiptap-editor/src/slash-command.ts

@@ -247,7 +247,7 @@ interface SlashPopup {
 }
 
 /** 校验图片/链接 URL:只允许 http(s) 和 data:image。拒绝 javascript: 等。 */
-function isValidUrl(url: string): boolean {
+export function isValidUrl(url: string): boolean {
   return /^https?:\/\//i.test(url) || /^data:image\//i.test(url)
 }
 

libs/tiptap-editor/src/upload-image.ts

@@ -21,7 +21,7 @@ export interface UploadNodeViewCallbacks {
  * NodeView 纯渲染，不发起上传——按钮点击转发给注入的 callbacks（实际是 coordinator）。
  * 属性变化时 ProseMirror 调 update(node)，NodeView 比较新旧 data-upload-state 重渲染遮罩。
  */
-class UploadImageNodeView {
+export class UploadImageNodeView {
   private node: PMNode
   private callbacks: UploadNodeViewCallbacks
   private uploadId: string | null