Refactor HomePage and PlaceholderPage layout for improved responsiveness

Removed the maximum width constraint from the HomePage container and increased the maximum width of the PlaceholderPage from 1180px to 1440px. These changes enhance layout flexibility and responsiveness, improving the overall user experience across different screen sizes.

src/components/pages/HomePage.tsx

@@ -28,7 +28,7 @@ export function HomePage({ onNavigate }: HomePageProps) {
           }}
         />
 
-        <div className="relative max-w-2xl">
+        <div className="relative">
           <h1 className="font-display display-xl text-ink">
             你好，开始管理你的智能视频助手
           </h1>

src/components/pages/PlaceholderPage.tsx

@@ -5,7 +5,7 @@ type PlaceholderPageProps = {
 
 export function PlaceholderPage({ title, description }: PlaceholderPageProps) {
   return (
-    <div className="mx-auto flex w-full max-w-[1180px] flex-col gap-8">
+    <div className="mx-auto flex w-full max-w-[1440px] flex-col gap-8">
       <div>
         <h1 className="font-display display-lg text-ink">{title}</h1>
         <p className="mt-3 max-w-2xl text-[15px] leading-7 text-muted-foreground">