feat: Optimize UI layout with fixed navigation and scrollable content

Layout Optimization:
- Fixed navigation bar at the top with sticky positioning
- Main content area now properly scrollable with flex layout
- Improved overall page structure for better UX

 Scrolling Enhancements:
- Added custom scrollbar styling for better visual appeal
- Implemented smooth scrolling behavior across the application
- Optimized scroll areas in ProjectDetails, TemplateManagement, AiClassificationSettings, and ModelList
- Added proper overflow handling for long content lists

 Visual Improvements:
- Beautiful custom scrollbars with hover effects
- Proper height constraints for content areas (calc(100vh-16rem))
- Enhanced scrolling experience with backdrop blur effects
- Added scroll indicators and shadow effects for better UX

 Responsive Design:
- Mobile-optimized scrolling behavior
- Proper touch scrolling on mobile devices
- Adaptive content heights for different screen sizes
- Maintained accessibility with reduced motion support

 Technical Improvements:
- Fixed JSX syntax errors in TemplateManagement and ModelList
- Improved component structure for better maintainability
- Added comprehensive CSS classes for scroll management
- Enhanced performance with optimized overflow handling

All pages now provide a smooth, professional scrolling experience while keeping the navigation always accessible.

apps/desktop/src/App.tsx

@@ -62,20 +62,22 @@ function App() {
 
   return (
     <Router>
-      <div className="min-h-screen bg-gradient-to-br from-gray-50 via-white to-gray-50">
-        {/* 导航栏 */}
+      <div className="h-screen flex flex-col bg-gradient-to-br from-gray-50 via-white to-gray-50">
+        {/* 固定的导航栏 */}
         <Navigation />
 
-        {/* 主要内容区域 */}
-        <main className="container mx-auto px-4 sm:px-6 lg:px-8 py-4 sm:py-6 lg:py-8 max-w-7xl">
-          <Routes>
-            <Route path="/" element={<ProjectList />} />
-            <Route path="/project/:id" element={<ProjectDetails />} />
-            <Route path="/models" element={<Models />} />
-            <Route path="/ai-classification-settings" element={<AiClassificationSettings />} />
-            <Route path="/templates" element={<TemplateManagement />} />
-            <Route path="/material-model-binding" element={<MaterialModelBinding />} />
-          </Routes>
+        {/* 可滚动的主要内容区域 */}
+        <main className="flex-1 overflow-y-auto smooth-scroll">
+          <div className="container mx-auto px-4 sm:px-6 lg:px-8 py-4 sm:py-6 lg:py-8 max-w-7xl min-h-full">
+            <Routes>
+              <Route path="/" element={<ProjectList />} />
+              <Route path="/project/:id" element={<ProjectDetails />} />
+              <Route path="/models" element={<Models />} />
+              <Route path="/ai-classification-settings" element={<AiClassificationSettings />} />
+              <Route path="/templates" element={<TemplateManagement />} />
+              <Route path="/material-model-binding" element={<MaterialModelBinding />} />
+            </Routes>
+          </div>
         </main>
 
         {/* 创建项目模态框 */}