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>

components/modes/liuyao-form.tsx

@@ -117,7 +117,7 @@ export default function LiuyaoForm() {
         />
       }
     >
-      <ZenCard title="问事 · 心意" subtitle="所求何事，心诚则灵">
+      <ZenCard title="问事 · 心意" subtitle="所求何事，心诚则灵" className="flex h-full min-h-0 flex-col">
         <Textarea
           placeholder="您想算点什么？"
           value={question}
@@ -139,7 +139,7 @@ export default function LiuyaoForm() {
         </div>
       </ZenCard>
 
-      <ZenCard title="起卦 · 时空" subtitle="地域、时辰与六爻">
+      <ZenCard title="起卦 · 时空" subtitle="地域、时辰与六爻" className="flex h-full min-h-0 flex-col">
         <RegionSelect
           label="起卦地域"
           provinceCode={provinceCode}