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/combined-form.tsx

@@ -156,7 +156,7 @@ export default function CombinedForm() {
         />
       }
     >
-      <ZenCard title="人和 · 生辰" subtitle="出生时空与地域">
+      <ZenCard title="人和 · 生辰" subtitle="出生时空与地域" className="flex h-full min-h-0 flex-col">
         <DateTimePicker
           label="出生日期 / 时间"
           date={birthDate}
@@ -195,7 +195,7 @@ export default function CombinedForm() {
         />
       </ZenCard>
 
-      <ZenCard title="天时地利 · 问事" subtitle="当前时空与所求">
+      <ZenCard title="天时地利 · 问事" subtitle="当前时空与所求" className="flex h-full min-h-0 flex-col">
         <RegionSelect
           label="当前所在地域"
           provinceCode={currentProvince}