refactor: 重构管理后台为现代化编辑风 UI 并改用模态交互

- 参考收集端落地页的奶油纸质感 + 深海蓝侧栏 + Playfair Display + 金/陶/玉配色，重塑整体视觉
- 编辑、二维码从跳转路由改为模态弹窗，新增"复制链接"快捷操作
- 抽取 Modal / Toast / QRCodeModal / PageHeader / FormPrimitives 通用基建
- 合并三份 QRCode 页面为统一组件，精简路由配置

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

packages/web/src/App.tsx

@@ -8,16 +8,9 @@ import AdminLogin from "./admin/AdminLogin";
 import AdminGuard from "./admin/AdminGuard";
 import AdminLayout from "./admin/AdminLayout";
 import StampList from "./admin/StampList";
-import StampForm from "./admin/StampForm";
-import StampQRCode from "./admin/StampQRCode";
 import ArticleList from "./admin/ArticleList";
-import ArticleForm from "./admin/ArticleForm";
-import ArticleQRCode from "./admin/ArticleQRCode";
 import MusicList from "./admin/MusicList";
-import MusicForm from "./admin/MusicForm";
-import MusicQRCode from "./admin/MusicQRCode";
 import RuleList from "./admin/RuleList";
-import RuleForm from "./admin/RuleForm";
 import RedemptionLog from "./admin/RedemptionLog";
 
 function CollectRedirect() {
@@ -41,20 +34,9 @@ export default function App() {
         <Route element={<AdminGuard />}>
           <Route element={<AdminLayout />}>
             <Route path="/admin/stamps" element={<StampList />} />
-            <Route path="/admin/stamps/new" element={<StampForm />} />
-            <Route path="/admin/stamps/:id/edit" element={<StampForm />} />
-            <Route path="/admin/stamps/:id/qrcode" element={<StampQRCode />} />
             <Route path="/admin/articles" element={<ArticleList />} />
-            <Route path="/admin/articles/new" element={<ArticleForm />} />
-            <Route path="/admin/articles/:id/edit" element={<ArticleForm />} />
-            <Route path="/admin/articles/:id/qrcode" element={<ArticleQRCode />} />
             <Route path="/admin/music" element={<MusicList />} />
-            <Route path="/admin/music/new" element={<MusicForm />} />
-            <Route path="/admin/music/:id/edit" element={<MusicForm />} />
-            <Route path="/admin/music/:id/qrcode" element={<MusicQRCode />} />
             <Route path="/admin/rules" element={<RuleList />} />
-            <Route path="/admin/rules/new" element={<RuleForm />} />
-            <Route path="/admin/rules/:id/edit" element={<RuleForm />} />
             <Route path="/admin/redemptions" element={<RedemptionLog />} />
           </Route>
         </Route>