feat(settings): 站点界面动画总开关与子开关

管理后台可关全站动画，并细调代码折叠、平滑滚动、装饰入场；统一 lib/motion，尊重系统减少动态效果。

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

frontend/components/MobilePostBar.tsx

@@ -3,6 +3,7 @@
 import { useEffect, useState } from "react";
 import { ArrowUp, MessageSquare } from "lucide-react";
 import LikeButton from "./LikeButton";
+import { scrollBehavior } from "@/lib/motion";
 
 /**
  * 帖子详情移动端浮动操作条（lg 以下显示）：
@@ -28,7 +29,7 @@ export default function MobilePostBar({
 
   const scrollToComments = () => {
     document.getElementById("comment-input")?.scrollIntoView({
-      behavior: window.matchMedia("(prefers-reduced-motion: reduce)").matches ? "auto" : "smooth",
+      behavior: scrollBehavior(),
       block: "center",
     });
   };
@@ -36,7 +37,7 @@ export default function MobilePostBar({
   const scrollToTop = () => {
     window.scrollTo({
       top: 0,
-      behavior: window.matchMedia("(prefers-reduced-motion: reduce)").matches ? "auto" : "smooth",
+      behavior: scrollBehavior(),
     });
   };
 

frontend/components/MotionProvider.tsx

@@ -0,0 +1,52 @@
+"use client";
+
+import { useEffect, type ReactNode } from "react";
+import {
+  applyMotionSiteConfig,
+  getMotionSiteConfig,
+  motionConfigFromSettings,
+  type MotionSiteConfig,
+} from "@/lib/motion";
+import { realtime, RT_SETTINGS_CHANGED, type RtSettingsData } from "@/lib/realtime";
+
+/**
+ * 根布局注入：SSR 初值写入 motion 模块 + html class；settings:changed 热更新。
+ */
+export default function MotionProvider({
+  initial,
+  children,
+}: {
+  initial: MotionSiteConfig;
+  children: ReactNode;
+}) {
+  useEffect(() => {
+    applyMotionSiteConfig(motionConfigFromSettings(initial));
+  }, [initial]);
+
+  useEffect(() => {
+    return realtime.on<RtSettingsData>(RT_SETTINGS_CHANGED, (data) => {
+      if (!data) return;
+      const cur = getMotionSiteConfig();
+      applyMotionSiteConfig(
+        motionConfigFromSettings({
+          ui_animations:
+            typeof data.ui_animations === "boolean"
+              ? data.ui_animations
+              : cur.ui_animations,
+          anim_code_fold:
+            typeof data.anim_code_fold === "boolean"
+              ? data.anim_code_fold
+              : cur.anim_code_fold,
+          anim_smooth_scroll:
+            typeof data.anim_smooth_scroll === "boolean"
+              ? data.anim_smooth_scroll
+              : cur.anim_smooth_scroll,
+          anim_chrome:
+            typeof data.anim_chrome === "boolean" ? data.anim_chrome : cur.anim_chrome,
+        })
+      );
+    });
+  }, []);
+
+  return children;
+}

frontend/components/PostToc.tsx

@@ -1,6 +1,7 @@
 "use client";
 
 import { useEffect, useRef, useState } from "react";
+import { scrollBehavior } from "@/lib/motion";
 
 export interface TocItem {
   level: 2 | 3;
@@ -44,13 +45,12 @@ export default function PostToc({ items }: { items: TocItem[] }) {
     }
     const el = navRef.current?.querySelector<HTMLElement>(`[data-toc-id="${active}"]`);
     if (!el) return;
-    const reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;
-    el.scrollIntoView({ block: "nearest", behavior: reduce ? "auto" : "smooth" });
+    el.scrollIntoView({ block: "nearest", behavior: scrollBehavior() });
   }, [active]);
 
   const jump = (id: string) => (e: React.MouseEvent) => {
     e.preventDefault();
-    document.getElementById(id)?.scrollIntoView({ behavior: "smooth", block: "start" });
+    document.getElementById(id)?.scrollIntoView({ behavior: scrollBehavior(), block: "start" });
   };
 
   return (

frontend/components/home/FeedNewTip.tsx

@@ -9,6 +9,7 @@ import {
   type RtFeedChangedData,
 } from "@/lib/realtime";
 import type { FeedSort } from "@/components/home/FeedTabs";
+import { scrollBehavior } from "@/lib/motion";
 
 interface FeedNewTipProps {
   sort: FeedSort;
@@ -52,7 +53,7 @@ export default function FeedNewTip({
   const handleClick = () => {
     setVisible(false);
     router.refresh();
-    window.scrollTo({ top: 0, behavior: "smooth" });
+    window.scrollTo({ top: 0, behavior: scrollBehavior() });
   };
 
   return (

frontend/components/markdown/MdCodeBlock.tsx

@@ -11,6 +11,7 @@ import {
 } from "react";
 import { Check, Copy, ChevronDown, ChevronUp } from "lucide-react";
 import { toast } from "@/lib/toast";
+import { allowMotion } from "@/lib/motion";
 import { useCodeFoldConfig } from "./CodeFoldProvider";
 
 const FOLD_ANIM_MS = 360;
@@ -34,10 +35,7 @@ function measureCollapsedPx(host: HTMLElement, foldLines: number): number {
 }
 
 function prefersReducedMotion(): boolean {
-  return (
-    typeof window !== "undefined" &&
-    window.matchMedia("(prefers-reduced-motion: reduce)").matches
-  );
+  return !allowMotion("codeFold");
 }
 
 type MdCodeBlockProps = HTMLAttributes<HTMLPreElement> & {