继续收口生成页顶部返回按钮

抽出生成页共用返回按钮壳并复用共享图标按钮能力
将自定义世界生成页接入共享返回按钮壳
将汪汪声浪生成页接入共享返回按钮壳并保留禁用态
补充两个生成页返回按钮的样式与交互回归测试

src/components/CustomWorldGenerationView.tsx

@@ -1,11 +1,10 @@
-import { ArrowLeft } from 'lucide-react';
-
 import type { CustomWorldGenerationProgress } from '../../packages/shared/src/contracts/runtime';
 import type { CustomWorldStructuredAnchorEntry } from '../services/customWorldAgentGenerationProgress';
 import { PlatformActionButton } from './common/PlatformActionButton';
 import { PlatformPillBadge } from './common/PlatformPillBadge';
 import {
   GenerationCurrentStepCard,
+  GenerationHeaderBackButton,
   GenerationPageBackdrop,
   GenerationProgressHero,
 } from './GenerationProgressHero';
@@ -137,14 +136,7 @@ export function CustomWorldGenerationView({
     <div className="relative isolate z-[1] -mx-3 -my-3 flex h-[calc(100%+1.5rem)] min-h-0 flex-col overflow-hidden bg-transparent px-4 pb-[max(1.25rem,env(safe-area-inset-bottom))] pt-4 text-[#3d1f10] sm:mx-0 sm:my-0 sm:h-full sm:rounded-[2rem] sm:px-5 sm:pt-5">
       <GenerationPageBackdrop />
       <div className="relative z-30 mb-4 flex shrink-0 items-center justify-between gap-3 py-2 sm:mb-5">
-        <button
-          type="button"
-          onClick={onBack}
-          className="inline-flex items-center gap-2 rounded-full bg-transparent px-0 py-2 text-xs font-black text-[#171411] sm:text-sm"
-        >
-          <ArrowLeft className="h-5 w-5 shrink-0" strokeWidth={2.6} />
-          <span className="break-keep">{backLabel}</span>
-        </button>
+        <GenerationHeaderBackButton label={backLabel} onClick={onBack} />
         <PlatformPillBadge
           tone="warning"
           size="xs"