fix: 统一卡片高度 - PersonCard 和 WithSpouse 卡片均设 min-h-[177px]

PersonCard（无配偶）原高 177px，WithSpouse（有配偶）原高 153px，
同行混排时高度不齐导致错行感。两种卡片统一最小高度 177px，
WithSpouse 内容区域垂直居中。

components/tree/family-node.tsx

@@ -223,7 +223,7 @@ function PersonCard({
     <div
       data-member-id={member.id}
       className={cn(
-        "family-node-card relative flex flex-col items-center p-4 transition-all duration-300 cursor-pointer w-[140px]",
+        "family-node-card relative flex flex-col items-center p-4 transition-all duration-300 cursor-pointer w-[140px] min-h-[177px] justify-center",
         // 现代简约中国风 - 圆角卡片
         "rounded-xl",
         "hover:scale-[1.03] hover:-translate-y-1",
@@ -553,7 +553,7 @@ export function FamilyNode({
   return (
     <div 
       className={cn(
-        "relative rounded-xl overflow-hidden transition-all duration-300",
+        "relative rounded-xl overflow-hidden transition-all duration-300 min-h-[177px] flex flex-col",
         "shadow-[0_4px_20px_rgba(0,0,0,0.08)] hover:shadow-[0_12px_40px_rgba(0,0,0,0.15)]",
         "hover:scale-[1.02] hover:-translate-y-1",
         isCardHighlighted
@@ -586,7 +586,7 @@ export function FamilyNode({
       )}
       
       {/* 内容区域 */}
-      <div className="p-3 pt-1 flex gap-3">
+      <div className="p-3 pt-1 flex gap-3 flex-1 items-center justify-center">
         {/* 主成员 */}
         <div 
           className={cn(