Support ultrawide layout with equal columns and taiji branding.

Use 50/50 mode workspace columns, widen content to 1920px on fish screens, replace header logo with taiji icon, and add full-page taiji backdrop.

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

app/page.tsx

@@ -2,6 +2,7 @@ import Link from "next/link";
 import PageShell from "@/components/page-shell";
 import { BookOpen, BrainCircuit, Compass, Sparkles } from "lucide-react";
 import { ZenCard } from "@/components/ui/zen-card";
+import { APP_CONTAINER } from "@/lib/layout";
 
 const MODULES = [
   {
@@ -36,7 +37,7 @@ const MODULES = [
 
 export default function Home() {
   return (
-    <PageShell className="max-w-4xl px-4 py-10 sm:py-14">
+    <PageShell className={`${APP_CONTAINER} py-10 sm:py-14`}>
       <div className="mb-10 text-center">
         <p className="text-4xl opacity-30">☯</p>
         <h1 className="mt-2 text-3xl font-bold tracking-[0.2em]">知命阁</h1>