feat(creator-studio): 图片宽度四档与作者行

- 通过 editor.BlockEdit 过滤器给 core/image 增加「半屏 / 中等 / 通栏 / 全宽」
  四档宽度，选中图片时出现在区块工具条；宽度写入 className 并序列化到
  post_content，前台样式即可生效，无需自定义区块或额外元数据
- 前台样式：半屏靠左 50%，中等 72%，通栏跟随正文行宽，全宽突破行宽但受容器
  内边距约束；移动端半屏与全宽回退为整行，避免横向滚动
- 新增作者行（头像 + 昵称 + 身份说明），数据由 CreatorRest::author_payload()
  从服务端给出，前端不自行拼装；无昵称时整行不渲染，头像缺失时回退首字占位
- 作者行放在摘要之后、正文之前

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

src/Core/CreatorRest.php

@@ -153,6 +153,8 @@ final class CreatorRest {
 				'titlePlaceholder' => (string) $settings['title_placeholder'],
 				'contentPlaceholder' => (string) $settings['content_placeholder'],
 			],
+			// 作者行数据由服务端给出，前端不自行拼装昵称/头像。
+			'author'     => $this->author_payload($editable, $user_id),
 			'privateUploads' => $this->private_upload_rows($user_id, $post_id),
 			'privateStorage' => PrivateAssets::is_available(),
 			'media'      => [
@@ -573,6 +575,37 @@ final class CreatorRest {
 		];
 	}
 
+	/**
+	 * 作者行数据：昵称、头像与身份说明。
+	 *
+	 * @return array{name:string,avatar:string,meta:string}
+	 */
+	private function author_payload(?\WP_Post $editable, int $user_id): array {
+		$author_id = $editable instanceof \WP_Post ? (int) $editable->post_author : $user_id;
+		$user      = $author_id > 0 ? get_userdata($author_id) : null;
+		if (!$user) {
+			return ['name' => '', 'avatar' => '', 'meta' => ''];
+		}
+
+		$avatar = function_exists('jio_get_avatar_url') ? (string) jio_get_avatar_url($author_id, ['size' => 64]) : '';
+		if ($avatar === '' && function_exists('get_avatar_url')) {
+			$avatar = (string) get_avatar_url($author_id, ['size' => 64]);
+		}
+
+		$meta = '';
+		if ($author_id !== $user_id) {
+			$meta = __('原作者', 'jio');
+		} elseif (function_exists('jio_get_user_vip_level') && (int) jio_get_user_vip_level($user_id) > 0) {
+			$meta = sprintf(__('VIP%s', 'jio'), (string) max(1, min(2, (int) jio_get_user_vip_level($user_id))));
+		}
+
+		return [
+			'name'   => (string) $user->display_name,
+			'avatar' => $avatar,
+			'meta'   => $meta,
+		];
+	}
+
 	/**
 	 * @param array<string, mixed> $post_meta
 	 * @return array<string, mixed>