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/bazi-form.tsx

@@ -109,7 +109,7 @@ export default function BaziForm() {
         />
       }
     >
-      <ZenCard title="出生 · 命局" subtitle="四柱排盘所需信息">
+      <ZenCard title="出生 · 命局" subtitle="四柱排盘所需信息" className="flex h-full min-h-0 flex-col">
         <DateTimePicker
           label="出生日期 / 时间"
           date={date}
@@ -148,7 +148,7 @@ export default function BaziForm() {
         />
       </ZenCard>
 
-      <ZenCard title="问事 · 排盘" subtitle="所求与命盘结果">
+      <ZenCard title="问事 · 排盘" subtitle="所求与命盘结果" className="flex h-full min-h-0 flex-col">
         <Textarea
           placeholder="事业、婚姻、健康等..."
           value={question}