收口前端平台组件库能力

新增 PlatformUiKit 通用弹窗、按钮、状态、空态、媒体、表单和标签等公共组件
迁移结果页、创作工作台、认证入口、RPG 暗色面板和运行态弹窗的重复 UI chrome
补充组件测试、页面回归测试、技术文档和 Hermes 共享决策记录

src/components/common/PlatformEmptyState.tsx

@@ -0,0 +1,75 @@
+import type { HTMLAttributes, ReactNode } from 'react';
+
+type PlatformEmptyStateSurface = 'soft' | 'dashed' | 'subpanel' | 'editorDark';
+type PlatformEmptyStateSize = 'compact' | 'panel' | 'inline';
+type PlatformEmptyStateTone = 'base' | 'soft';
+
+type PlatformEmptyStateProps = Omit<
+  HTMLAttributes<HTMLDivElement>,
+  'children'
+> & {
+  children: ReactNode;
+  surface?: PlatformEmptyStateSurface;
+  size?: PlatformEmptyStateSize;
+  tone?: PlatformEmptyStateTone;
+};
+
+const PLATFORM_EMPTY_STATE_SURFACE_CLASS: Record<
+  PlatformEmptyStateSurface,
+  string
+> = {
+  soft: 'platform-surface platform-surface--soft rounded-[1.35rem]',
+  dashed:
+    'rounded-[1.35rem] border border-dashed border-[var(--platform-subpanel-border)] bg-white/52',
+  subpanel:
+    'rounded-[1rem] border border-[var(--platform-subpanel-border)] bg-white/74',
+  editorDark: 'rounded-2xl border border-dashed border-white/12 bg-black/20',
+};
+
+const PLATFORM_EMPTY_STATE_SIZE_CLASS: Record<PlatformEmptyStateSize, string> =
+  {
+    compact: 'px-4 py-3 text-sm leading-6',
+    panel:
+      'flex min-h-[14rem] items-center justify-center px-6 text-center text-sm',
+    inline: 'px-4 py-5 text-center text-sm font-semibold',
+  };
+
+const PLATFORM_EMPTY_STATE_TONE_CLASS: Record<PlatformEmptyStateTone, string> =
+  {
+    base: 'text-[var(--platform-text-base)]',
+    soft: 'text-[var(--platform-text-soft)]',
+  };
+
+/**
+ * 平台通用空态和轻量加载态。
+ * 收口平台列表、作品架和素材选择弹窗中重复的空面板外观。
+ */
+export function PlatformEmptyState({
+  children,
+  surface = 'soft',
+  size = 'compact',
+  tone,
+  className,
+  ...divProps
+}: PlatformEmptyStateProps) {
+  const resolvedTone =
+    tone ?? (surface === 'subpanel' || size === 'inline' ? 'soft' : 'base');
+
+  return (
+    <div
+      {...divProps}
+      className={[
+        'min-w-0',
+        'platform-empty-state',
+        PLATFORM_EMPTY_STATE_SURFACE_CLASS[surface],
+        PLATFORM_EMPTY_STATE_SIZE_CLASS[size],
+        PLATFORM_EMPTY_STATE_TONE_CLASS[resolvedTone],
+        className,
+      ]
+        .filter(Boolean)
+        .join(' ')}
+    >
+      {children}
+    </div>
+  );
+}