feat: 站点单页、时间线导入与行级 BBCode 短代码

首页右栏接入单页入口与公告置顶/全部页；Markdown 编辑器支持可视化时间线与 Git 导入；隐藏块改为 [hide]/[timeline] 命名闭合，并修复单页/公告 GORM 更新只改 updated_at 的问题。

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

frontend/components/markdown/MdHideBlock.tsx

@@ -27,6 +27,8 @@ type MdHideBlockProps = {
   points?: number;
   locked?: boolean;
   postId?: number;
+  /** 登录跳转路径（公告等无 postId 时使用） */
+  loginHref?: string;
   loggedIn?: boolean;
   children?: ReactNode;
 };
@@ -37,6 +39,7 @@ export default function MdHideBlock({
   points = 0,
   locked = false,
   postId,
+  loginHref,
   loggedIn = false,
   children,
 }: MdHideBlockProps) {
@@ -46,6 +49,9 @@ export default function MdHideBlock({
   const [pwd, setPwd] = useState("");
   const [pwdError, setPwdError] = useState("");
   const label = hideKindLabel(kind);
+  const loginTo =
+    loginHref ||
+    (postId ? `/login?redirect=${encodeURIComponent(`/post/${postId}`)}` : "/login");
 
   if (locked) {
     const unlockPoints = async () => {
@@ -115,11 +121,8 @@ export default function MdHideBlock({
                 : "登录后即可阅读此段"}
         </p>
         <div className="j13-hide-gate-actions">
-          {kind === "login" && !loggedIn && postId && (
-            <Link
-              href={`/login?redirect=${encodeURIComponent(`/post/${postId}`)}`}
-              className="btn btn-primary"
-            >
+          {kind === "login" && !loggedIn && (
+            <Link href={loginTo} className="btn btn-primary">
               去登录
             </Link>
           )}
@@ -133,23 +136,24 @@ export default function MdHideBlock({
               {busy ? "解锁中…" : `支付 ${points || 0} 积分解锁`}
             </button>
           )}
-          {kind === "points" && !loggedIn && postId && (
-            <Link
-              href={`/login?redirect=${encodeURIComponent(`/post/${postId}`)}`}
-              className="btn btn-primary"
-            >
+          {kind === "points" && !loggedIn && (
+            <Link href={loginTo} className="btn btn-primary">
               登录后解锁
             </Link>
           )}
-          {kind === "reply" && postId && !loggedIn && (
+          {kind === "reply" && !loggedIn && (
             <Link
-              href={`/login?redirect=${encodeURIComponent(`/post/${postId}#comment-input`)}`}
+              href={
+                postId
+                  ? `/login?redirect=${encodeURIComponent(`/post/${postId}#comment-input`)}`
+                  : loginTo
+              }
               className="btn btn-primary"
             >
               登录后去回复
             </Link>
           )}
-          {kind === "reply" && loggedIn && (
+          {kind === "reply" && loggedIn && postId && (
             <a
               href="#comment-input"
               className="btn btn-primary"