公开页补齐自引用 Canonical 与按类型的结构化数据，图片补上说明文字。

后台设置和内容编辑改成可导航布局；部署用访客 origin 生成 Canonical，避免落到容器地址。

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

frontend/hooks/useUnsavedGuard.ts

@@ -0,0 +1,69 @@
+"use client";
+
+import { useEffect, useRef, useState } from "react";
+import { usePathname, useRouter } from "next/navigation";
+
+/**
+ * 有未保存修改时：关闭/刷新走 beforeunload；站内链接先确认再跳转。
+ * 未修改时不打扰。hash 分类切换由调用方自行拦截。
+ */
+export default function useUnsavedGuard(dirty: boolean) {
+  const router = useRouter();
+  const pathname = usePathname();
+  const dirtyRef = useRef(dirty);
+  dirtyRef.current = dirty;
+  const [pendingHref, setPendingHref] = useState<string | null>(null);
+
+  useEffect(() => {
+    const onBeforeUnload = (e: BeforeUnloadEvent) => {
+      if (!dirtyRef.current) return;
+      e.preventDefault();
+      e.returnValue = "";
+    };
+    window.addEventListener("beforeunload", onBeforeUnload);
+    return () => window.removeEventListener("beforeunload", onBeforeUnload);
+  }, []);
+
+  useEffect(() => {
+    const onClick = (e: MouseEvent) => {
+      if (!dirtyRef.current) return;
+      if (e.defaultPrevented || e.button !== 0 || e.metaKey || e.ctrlKey || e.shiftKey || e.altKey) {
+        return;
+      }
+      const target = e.target;
+      if (!(target instanceof Element)) return;
+      const a = target.closest("a[href]");
+      if (!a) return;
+      const href = a.getAttribute("href");
+      if (!href || href.startsWith("#") || href.startsWith("mailto:") || href.startsWith("javascript:")) return;
+      let url: URL;
+      try {
+        url = new URL(href, window.location.href);
+      } catch {
+        return;
+      }
+      if (url.origin !== window.location.origin) return;
+      const next = `${url.pathname}${url.search}${url.hash}`;
+      const cur = `${pathname}${window.location.search}${window.location.hash}`;
+      if (next === cur) return;
+      e.preventDefault();
+      e.stopPropagation();
+      setPendingHref(next);
+    };
+    document.addEventListener("click", onClick, true);
+    return () => document.removeEventListener("click", onClick, true);
+  }, [pathname]);
+
+  const confirmLeave = () => {
+    if (!pendingHref) return;
+    const href = pendingHref;
+    setPendingHref(null);
+    router.push(href);
+  };
+
+  return {
+    leaveOpen: pendingHref != null,
+    confirmLeave,
+    cancelLeave: () => setPendingHref(null),
+  };
+}