feat: 公文三栏单页布局，并修复时间线目录跳转与样式

公告/单页对齐帖子详情三栏壳；时间线按日锚点可跳转，条目改为日志行并用暖金日期区分 feat 色。

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

frontend/lib/toc.ts

@@ -0,0 +1,102 @@
+import type { TocItem } from "@/components/PostToc";
+
+const TIMELINE_DAY_RE = /^##\s+(\d{4}-\d{2}-\d{2})\s+(.+)$/;
+const HEADING_RE = /^(#{2,3})\s+(.+?)\s*#*\s*$/;
+const HIDE_OPEN_RE = /^\[hide(?:\s+.+)?\]$/i;
+
+/** 时间线日分组锚点 id（与 MdTimeline 一致） */
+export function timelineDayId(date: string): string {
+  if (/^\d{4}-\d{2}-\d{2}$/.test(date)) return `tl-${date}`;
+  return `tl-${date.replace(/[^a-zA-Z0-9_-]+/g, "-").replace(/^-+|-+$/g, "") || "unknown"}`;
+}
+
+/**
+ * 从正文提取目录：
+ * - 块外 ## / ### → h-{n}（供 headingRenderer 按序挂 id）
+ * - [timeline] 内按日期去重 → tl-YYYY-MM-DD（日分组锚点）
+ * - 代码围栏 / [hide] 块内标题不计入
+ */
+export function extractToc(content: string): TocItem[] {
+  const items: TocItem[] = [];
+  let inCode = false;
+  let inTimeline = false;
+  let inHide = false;
+  let headingCount = 0;
+  /** 当前 timeline 块内出现过的日期（保持文件顺序，收块时再按日倒序发出） */
+  let timelineDates: string[] = [];
+  const timelineSeen = new Set<string>();
+
+  const flushTimelineDates = () => {
+    if (timelineDates.length === 0) return;
+    const sorted = [...timelineDates].sort((a, b) => (a < b ? 1 : a > b ? -1 : 0));
+    for (const date of sorted) {
+      items.push({ level: 2, text: date, id: timelineDayId(date) });
+    }
+    timelineDates = [];
+    timelineSeen.clear();
+  };
+
+  for (const raw of content.replace(/\r\n/g, "\n").replace(/\r/g, "\n").split("\n")) {
+    const line = raw.trim();
+
+    if (line.startsWith("```")) {
+      inCode = !inCode;
+      continue;
+    }
+    if (inCode) continue;
+
+    const lower = line.toLowerCase();
+
+    if (!inHide && !inTimeline && lower === "[timeline]") {
+      inTimeline = true;
+      continue;
+    }
+    if (inTimeline && lower === "[/timeline]") {
+      inTimeline = false;
+      flushTimelineDates();
+      continue;
+    }
+    if (inTimeline) {
+      const tm = TIMELINE_DAY_RE.exec(line);
+      if (tm && !timelineSeen.has(tm[1])) {
+        timelineSeen.add(tm[1]);
+        timelineDates.push(tm[1]);
+      }
+      continue;
+    }
+
+    if (!inHide && HIDE_OPEN_RE.test(line)) {
+      inHide = true;
+      continue;
+    }
+    if (inHide && lower === "[/hide]") {
+      inHide = false;
+      continue;
+    }
+    if (inHide) continue;
+
+    const m = HEADING_RE.exec(line);
+    if (m) {
+      items.push({
+        level: m[1].length as 2 | 3,
+        text: m[2],
+        id: `h-${headingCount++}`,
+      });
+    }
+  }
+
+  // 未闭合的 timeline 也尽量发出已收集日期
+  flushTimelineDates();
+  return items;
+}
+
+/** 仅正文 Markdown 标题（排除时间线日锚点），供 headingRenderer 按序挂 id */
+export function markdownHeadingToc(toc: TocItem[]): TocItem[] {
+  return toc.filter((t) => /^h-\d+$/.test(t.id));
+}
+
+/** 粗略阅读时长：约 400 字/分钟，至少 1 分钟 */
+export function estimateReadingMinutes(text: string, fallbackLen = 0): number {
+  const len = text.trim().length > 0 ? text.trim().length : fallbackLen;
+  return Math.max(1, Math.ceil(len / 400));
+}