继续收口暗色弹窗底部动作区

新增 PlatformDarkModalFooter 统一 dark modal footer 的布局壳
接入 NPC 弹窗、选择定制弹窗、任务更新弹层与物品详情 footer
补充组件级与弹窗集成测试并更新收口计划和共享决策记录

src/components/common/PlatformDarkModalFooter.tsx

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+import type { ComponentPropsWithoutRef, ReactNode } from 'react';
+
+type PlatformDarkModalFooterLayout = 'actions' | 'content';
+type PlatformDarkModalFooterPadding = 'compact' | 'roomy' | 'bottom';
+type PlatformDarkModalFooterGap = 'sm' | 'md';
+type PlatformDarkModalFooterAlign = 'start' | 'center' | 'end' | 'between';
+
+type PlatformDarkModalFooterProps = ComponentPropsWithoutRef<'div'> & {
+  children: ReactNode;
+  bordered?: boolean;
+  layout?: PlatformDarkModalFooterLayout;
+  padding?: PlatformDarkModalFooterPadding;
+  gap?: PlatformDarkModalFooterGap;
+  wrap?: boolean;
+  align?: PlatformDarkModalFooterAlign;
+  contentClassName?: string;
+};
+
+const PADDING_CLASS: Record<PlatformDarkModalFooterPadding, string> = {
+  compact: 'px-4 py-3 sm:px-5 sm:py-4',
+  roomy: 'px-5 py-4',
+  bottom: 'px-5 pb-5',
+};
+
+const GAP_CLASS: Record<PlatformDarkModalFooterGap, string> = {
+  sm: 'gap-2',
+  md: 'gap-3',
+};
+
+const ALIGN_CLASS: Record<PlatformDarkModalFooterAlign, string> = {
+  start: 'justify-start',
+  center: 'justify-center',
+  end: 'justify-end',
+  between: 'justify-between',
+};
+
+/**
+ * 暗色 / 像素弹层底部 footer 骨架。
+ * 统一承接 border、padding 和常见的动作按钮排布，避免业务页重复手写同一套 chrome。
+ */
+export function PlatformDarkModalFooter({
+  children,
+  bordered = true,
+  layout = 'actions',
+  padding = 'compact',
+  gap = 'md',
+  wrap = false,
+  align = 'end',
+  className,
+  contentClassName,
+  ...props
+}: PlatformDarkModalFooterProps) {
+  const frameClassName = [
+    'platform-dark-modal-footer',
+    bordered ? 'border-t border-white/10' : null,
+    PADDING_CLASS[padding],
+    className ?? null,
+  ]
+    .filter(Boolean)
+    .join(' ');
+
+  if (layout === 'content') {
+    return (
+      <div className={frameClassName} {...props}>
+        {children}
+      </div>
+    );
+  }
+
+  const actionsClassName = [
+    'platform-dark-modal-footer__actions',
+    'flex items-center',
+    ALIGN_CLASS[align],
+    GAP_CLASS[gap],
+    wrap ? 'flex-wrap' : null,
+    contentClassName ?? null,
+  ]
+    .filter(Boolean)
+    .join(' ');
+
+  return (
+    <div className={frameClassName} {...props}>
+      <div className={actionsClassName}>{children}</div>
+    </div>
+  );
+}