refactor(creator-studio): pick the cover from the toolbar image dialog

The cover row carried its own hidden file input and upload call, so authors
had two different image flows in one page.

- 添加封面 now opens window.JioSubmitMedia with type=image, the same dialog
  the toolbar's 图片 button uses (mine / upload / external link).
- The picked image is stored as the full-size URL plus its attachment id,
  matching FrontSubmitFeatured's image branch, which re-checks ownership
  and sets the post thumbnail.
- Removes the now-unused uploadCover path, apiUpload/nonce imports, and the
  .jio-creator__cover-input rule.

Contract added; 887 widget-system tests pass.

assets/creator-studio/src/components/publish-settings.tsx

@@ -8,10 +8,9 @@
  * @package Jio
  */
 
-import { useMemo, useRef, useState } from '@wordpress/element';
+import { useMemo, useState } from '@wordpress/element';
 import { __, sprintf } from '@wordpress/i18n';
 
-import { apiUpload } from '../services/api';
 import type { PayState } from '../draft';
 
 type Featured = { type: string; data: Record<string, any>; mediaId?: number };
@@ -78,9 +77,7 @@ export function PublishSettings({
 	onCustomChange,
 	onOpenPaySettings,
 }: Props) {
-	const coverInput = useRef<HTMLInputElement | null>(null);
 	const [tagInput, setTagInput] = useState('');
-	const [uploading, setUploading] = useState(false);
 	const [error, setError] = useState('');
 	const minSchedule = useMemo(() => toLocalInput(new Date(Date.now() + 5 * 60 * 1000)), []);
 	const coverUrl = typeof featured?.data?.url === 'string' ? featured.data.url : '';
@@ -112,30 +109,37 @@ export function PublishSettings({
 		});
 	};
 
-	const uploadCover = async () => {
-		const file = coverInput.current?.files?.[0];
-		const uploadUrl = bootstrap.media?.uploadUrl?.image;
-		if (!file || !uploadUrl) {
+	/**
+	 * 复用工具栏「图片」按钮的媒体弹窗选封面。
+	 *
+	 * 与正文插图走同一个 JioSubmitMedia：可以直接从「我的图片」挑，
+	 * 也可以当场上传或填外链，作者不必在两套上传 UI 之间切换。
+	 */
+	const pickCover = () => {
+		const media = (window as any).JioSubmitMedia;
+		if (!media || typeof media.open !== 'function') {
+			setError(__('媒体选择器尚未加载，请刷新页面后重试。', 'jio'));
 			return;
 		}
 		setError('');
-		setUploading(true);
-		try {
-			const response = await apiUpload(uploadUrl, file, nonce);
-			const id = Number(response.attachment_id || response.id || 0);
-			const url = String(response.url || '');
-			if (!id || !url) {
-				throw new Error(__('上传后无法读取图片。', 'jio'));
-			}
-			onFeaturedChange({ type: 'image', mediaId: id, data: { id, url } });
-		} catch (uploadError: any) {
-			setError(String(uploadError?.message || __('上传失败', 'jio')));
-		} finally {
-			setUploading(false);
-			if (coverInput.current) {
-				coverInput.current.value = '';
-			}
-		}
+		media.open({
+			type: 'image',
+			multiple: false,
+			onSelect: (selected: any) => {
+				const item = Array.isArray(selected) ? selected[0] : selected;
+				if (!item) {
+					return;
+				}
+				// 封面按原图保存，预览才用缩略图，避免分享卡片被压成小图。
+				const url = String(item.url || item.large_url || '');
+				if (!url) {
+					setError(__('无法读取图片地址，请重新选择。', 'jio'));
+					return;
+				}
+				const id = Number(item.attachment_id || item.id || 0);
+				onFeaturedChange({ type: 'image', mediaId: id, data: { id, url } });
+			},
+		});
 	};
 
 	return (
@@ -245,7 +249,7 @@ export function PublishSettings({
 								<button
 									type="button"
 									className="jio-creator__cover-preview"
-									onClick={() => coverInput.current?.click()}
+									onClick={pickCover}
 									aria-label={__('更换封面', 'jio')}
 								>
 									<img src={coverUrl} alt="" />
@@ -260,23 +264,11 @@ export function PublishSettings({
 								</button>
 							</>
 						) : (
-							<button
-								type="button"
-								className="jio-creator__cover-add"
-								onClick={() => coverInput.current?.click()}
-								disabled={uploading}
-							>
+							<button type="button" className="jio-creator__cover-add" onClick={pickCover}>
 								<i className="fa fas fa-plus" aria-hidden="true" />
-								<span>{uploading ? __('上传中…', 'jio') : __('添加封面', 'jio')}</span>
+								<span>{__('添加封面', 'jio')}</span>
 							</button>
 						)}
-						<input
-							ref={coverInput}
-							type="file"
-							accept="image/*"
-							className="jio-creator__cover-input"
-							onChange={() => void uploadCover()}
-						/>
 					</div>
 				</div>
 			)}

assets/creator-studio/src/styles/studio.scss

@@ -699,15 +699,6 @@ body.jio-page-submit.has-static-nav {
 	gap: 8px;
 }
 
-.jio-creator__cover-input {
-	position: absolute;
-	width: 1px;
-	height: 1px;
-	overflow: hidden;
-	opacity: 0;
-	pointer-events: none;
-}
-
 .jio-creator__cover-add {
 	display: inline-flex;
 	align-items: center;