升级帖子编辑与 Feed 体验：TipTap 富文本、修订历史、排序与编辑时限。

将 Markdown 编辑器替换为 TipTap WYSIWYG，新增帖子修订记录与 diff 展示；首页支持最新/回复排序与本地缓存；后台可配置编辑时限与锁定帖子；侧边栏整合板块导航并优化 Feed 布局。

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/src/components/editor/MembersOnlyExtension.tsx

@@ -0,0 +1,84 @@
+import { Node, mergeAttributes } from '@tiptap/core';
+import {
+  ReactNodeViewRenderer,
+  NodeViewWrapper,
+  NodeViewContent,
+  type NodeViewProps,
+} from '@tiptap/react';
+import { LockKeyhole } from 'lucide-react';
+
+/** 编辑态「登录可见」区块视图 */
+function MembersOnlyView({ selected }: NodeViewProps) {
+  return (
+    <NodeViewWrapper
+      as="members-only"
+      className={`post-members-only post-members-only--visible editor-members-only${selected ? ' editor-members-only--selected' : ''}`}
+    >
+      <div className="post-members-only__badge" contentEditable={false}>
+        <span className="post-members-only__badge-icon" aria-hidden="true">
+          <LockKeyhole size={12} />
+        </span>
+        <span>登录可见</span>
+      </div>
+      <NodeViewContent className="post-members-only__body" />
+    </NodeViewWrapper>
+  );
+}
+
+declare module '@tiptap/core' {
+  interface Commands<ReturnType> {
+    membersOnly: {
+      insertMembersOnly: () => ReturnType;
+      wrapMembersOnly: () => ReturnType;
+    };
+  }
+}
+
+/** TipTap 自定义节点：登录可见内容区块 */
+export const MembersOnly = Node.create({
+  name: 'membersOnly',
+  group: 'block',
+  content: 'block+',
+  defining: true,
+  isolating: true,
+
+  parseHTML() {
+    return [{ tag: 'members-only' }];
+  },
+
+  renderHTML({ HTMLAttributes }) {
+    return ['members-only', mergeAttributes(HTMLAttributes), 0];
+  },
+
+  addNodeView() {
+    return ReactNodeViewRenderer(MembersOnlyView);
+  },
+
+  addCommands() {
+    return {
+      insertMembersOnly: () => ({ chain }) => chain()
+        .insertContent({
+          type: this.name,
+          content: [{
+            type: 'paragraph',
+            content: [{ type: 'text', text: '在此输入仅登录用户可见的内容…' }],
+          }],
+        })
+        .run(),
+
+      wrapMembersOnly: () => ({ tr, state, dispatch }) => {
+        const { from, to, empty } = state.selection;
+        if (empty) return false;
+
+        const slice = state.doc.slice(from, to);
+        if (!slice.content.size) return false;
+
+        const node = state.schema.nodes.membersOnly.create(null, slice.content);
+        if (dispatch) {
+          tr.replaceRangeWith(from, to, node);
+        }
+        return true;
+      },
+    };
+  },
+});