新增社区页面路由，更新底部导航以移除占位符，优化音量控制按钮样式和功能

client/src/components/BottomNav.tsx

@@ -19,11 +19,10 @@ interface NavItem {
   path: string;
   icon: React.ComponentType<{ size?: number; className?: string }>;
   label: string;
-  placeholder?: boolean;
 }
 
 const NAV_ITEMS: NavItem[] = [
-  { path: "/community", icon: MessageSquare, label: "社区", placeholder: true },
+  { path: "/community", icon: MessageSquare, label: "社区" },
   { path: "/eq", icon: Sliders, label: "HP-EQ" },
   { path: "/", icon: Home, label: "主页" },
   { path: "/effects", icon: Activity, label: "Effect" },
@@ -53,7 +52,7 @@ export default function BottomNav() {
           const Icon = item.icon;
 
           return (
-            <Link key={item.path} href={item.placeholder ? "#" : item.path}>
+            <Link key={item.path} href={item.path}>
               <div className="flex flex-col items-center justify-center relative pt-2.5 pb-1.5 px-3">
                 {/* Active indicator bar */}
                 <div