refactor(eq): 优化频率图表Y轴刻度范围菜单交互

- 将ChangelogPage修改为懒加载，减少主入口chunk体积
- 在频率图表中添加Y轴刻度范围按钮，支持点击展开下拉菜单选择范围
- 实现点击菜单外部自动收起功能，提升用户体验
- 调整Y轴刻度标签显示，避免与按钮重叠
- 移除原有的刻度范围切换静态按钮，改用动态菜单方式展示
- 更新相关样式，提升界面一致性和美观性

client/src/App.tsx

@@ -16,7 +16,6 @@ import IOPage from "./pages/IOPage";
 import VUPage from "./pages/VUPage";
 import SelectPage, { consumeSelectReturnScroll } from "./pages/SelectPage";
 import CommunityPage from "./pages/CommunityPage";
-import ChangelogPage from "./pages/ChangelogPage";
 import { AIDrawerProvider } from "./contexts/AIDrawerContext";
 import { NavConfigProvider, useNavConfig } from "./contexts/NavConfigContext";
 import DesktopAIShell from "./components/DesktopAIShell";
@@ -25,6 +24,8 @@ import { appShellColumnClass, appShellOuterClass } from "./lib/appShell";
 const EQPage = lazy(() => import("./pages/EQPage"));
 const EffectsPage = lazy(() => import("./pages/EffectsPage"));
 const AIPage = lazy(() => import("./pages/AIPage"));
+// ChangelogPage 依赖 streamdown（shiki/mermaid/katex 重链），懒加载避免打入主入口 chunk
+const ChangelogPage = lazy(() => import("./pages/ChangelogPage"));
 
 function LazyRoute({ children }: { children: React.ReactNode }) {
   return <Suspense fallback={<PageLoader />}>{children}</Suspense>;
@@ -54,6 +55,14 @@ function EffectsPageRoute() {
   );
 }
 
+function ChangelogPageRoute() {
+  return (
+    <LazyRoute>
+      <ChangelogPage />
+    </LazyRoute>
+  );
+}
+
 /**
  * Restores the calling page's scroll position when returning from /select.
  * The select page is short, so the browser clamps window scroll to 0 while on
@@ -106,7 +115,7 @@ function AppRouter() {
       <Route path="/select" component={SelectPage} />
       <Route path="/ai" component={AIPageRoute} />
       <Route path="/community" component={CommunityPage} />
-      <Route path="/changelog" component={ChangelogPage} />
+      <Route path="/changelog" component={ChangelogPageRoute} />
       <Route path="/404" component={NotFound} />
       <Route component={NotFound} />
     </Switch>

client/src/pages/eq/components/FreqChart.tsx

@@ -1,4 +1,5 @@
 import { useState, useEffect, useRef, useMemo } from "react";
+import { ChevronDown, ZoomIn } from "lucide-react";
 import { toast } from "sonner";
 import { useStrokeDrawAnimation } from "@/lib/useStrokeDrawAnimation";
 import {
@@ -113,6 +114,22 @@ export function FreqChart({
     }
   };
 
+  const [isYRangeMenuOpen, setIsYRangeMenuOpen] = useState(false);
+  const yRangeMenuRef = useRef<HTMLDivElement | null>(null);
+
+  // 点击菜单外部收起下拉
+  useEffect(() => {
+    if (!isYRangeMenuOpen) return;
+    const onPointerDown = (event: PointerEvent) => {
+      const target = event.target as Node;
+      if (!(yRangeMenuRef.current?.contains(target) ?? false)) {
+        setIsYRangeMenuOpen(false);
+      }
+    };
+    document.addEventListener("pointerdown", onPointerDown);
+    return () => document.removeEventListener("pointerdown", onPointerDown);
+  }, [isYRangeMenuOpen]);
+
   useEffect(() => {
     const node = chartContainerRef.current;
     if (!node) return;
@@ -317,27 +334,6 @@ export function FreqChart({
             Equalized
           </span>
         </button>
-        {/* Y 轴刻度范围切换 */}
-        <div
-          className="ml-auto flex shrink-0 items-center overflow-hidden rounded-[8px]"
-          style={{ background: "rgba(44,44,46,0.7)", border: "1px solid rgba(255,255,255,0.08)" }}
-        >
-          {Y_RANGE_OPTIONS.map((r) => (
-            <button
-              key={r}
-              type="button"
-              className="px-2 py-1 text-[10px] transition-all duration-150"
-              style={
-                yDbMax === r
-                  ? { background: "#00FFF6", color: "#000", fontWeight: 600 }
-                  : { color: "rgba(255,255,255,0.4)" }
-              }
-              onClick={() => handleYRangeChange(r)}
-            >
-              ±{r}
-            </button>
-          ))}
-        </div>
       </div>
 
       {/* A/B + DIFF controls */}
@@ -399,9 +395,43 @@ export function FreqChart({
       {/* SVG chart */}
       <div
         ref={chartContainerRef}
-        className="rounded-[10px] overflow-hidden"
+        className="relative rounded-[10px] overflow-hidden"
         style={{ background: "rgba(10,12,10,0.7)" }}
       >
+        {/* Y 轴刻度范围：Y 轴顶端单按钮，点击展开下拉选项 */}
+        <div ref={yRangeMenuRef} className="absolute left-1 top-1 z-20">
+          <button
+            type="button"
+            className="flex items-center gap-1 rounded-[8px] px-2 py-1 text-[12px] font-semibold text-[#00FFF6] active:opacity-80 transition-opacity"
+            style={{ background: "rgba(44,44,46,0.85)", border: "1px solid rgba(255,255,255,0.12)" }}
+            onClick={() => setIsYRangeMenuOpen(v => !v)}
+          >
+            <ZoomIn size={12} />
+            {yDbMax}
+            <ChevronDown size={12} className={`transition-transform ${isYRangeMenuOpen ? "rotate-180" : ""}`} />
+          </button>
+          {isYRangeMenuOpen && (
+            <div
+              className="absolute left-0 top-full mt-1 w-[64px] overflow-hidden rounded-[8px]"
+              style={{ background: "rgba(10,12,16,0.98)", border: "1px solid rgba(0,255,246,0.35)", boxShadow: "0 8px 20px rgba(0,0,0,0.45)" }}
+            >
+              {Y_RANGE_OPTIONS.map((r) => (
+                <button
+                  key={r}
+                  type="button"
+                  className={`w-full px-2 py-1.5 text-left text-[11px] transition-colors ${yDbMax === r ? "text-black font-semibold" : "text-white/90 hover:bg-white/10"}`}
+                  style={yDbMax === r ? { background: "#00FFF6" } : undefined}
+                  onClick={() => {
+                    handleYRangeChange(r);
+                    setIsYRangeMenuOpen(false);
+                  }}
+                >
+                  {r}
+                </button>
+              ))}
+            </div>
+          )}
+        </div>
         <svg
           ref={svgRef}
           viewBox={`0 0 ${W} ${H}`}
@@ -419,13 +449,16 @@ export function FreqChart({
             </clipPath>
           </defs>
           {/* dB grid */}
-          {gainLabels.map((g) => (
+          {gainLabels.map((g, gi) => (
             <g key={`gain-${g}`}>
               <line x1="0" y1={gainToY(g)} x2={W} y2={gainToY(g)}
                 stroke="rgba(255,255,255,0.05)" strokeWidth="1" />
+              {/* 顶格标签位置被 Y 轴范围按钮占用，避免文字重叠 */}
+              {gi > 0 && (
                 <text x="3" y={gainToY(g) - 2} fontSize="7" fill="rgba(255,255,255,0.2)">
                   {formatGainLabel(g)}
                 </text>
+              )}
             </g>
           ))}
           {/* Freq grid */}