Fix/统一修复modal样式失效 (#122)

之前遇到几次弹窗的样式不生效,bug 现在在画布agent的删除对话弹窗又出现了,
这个pr把类似的修改集中到最下层的UnifiedModal,适用于所有的modal,
一些特殊的modal有特殊处理.

画布agent的删除对话弹窗
![shotmd-1785399342.jpg](/attachments/d63d7dc6-bf7e-4f13-bfe8-bc4716cd798f)

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Co-authored-by: 段舒康 <kdletters@qq.com>
Reviewed-on: http://192.168.35.82/git/GenarrativeAI/Genarrative/pulls/122
Reviewed-by: 段舒康 <kdletters@qq.com>
Co-authored-by: 王德宇 <kvtodev@outlook.com>
Co-committed-by: 王德宇 <kvtodev@outlook.com>

src/components/auth/PlatformAuthModalShell.tsx

@@ -57,9 +57,10 @@ export function PlatformAuthModalShell({
       closeOnEscape={false}
       size={size}
       showHeader={showHeader}
+      portalTheme={platformTheme}
       zIndexClassName={zIndexClassName}
       overlayClassName={joinClassNames(
-        `platform-theme platform-theme--${platformTheme} text-[var(--platform-text-strong)]`,
+        'text-[var(--platform-text-strong)]',
         overlaySpacing === 'default' && '!px-3 !py-4 sm:!p-4',
         overlayClassName,
       )}