feat: add forum seed categories, improve page layouts and navigation

- Seed default forum categories (announcements, learning, feedback) on startup
- Update forum pages with improved category/post/reply UI
- Refine navbar, mobile nav, and home page content layout
- Improve analytics, course-content, knowledge, profile, settings, spatial pages

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

web/src/app/(main)/course-content/page.tsx

@@ -93,32 +93,20 @@ export default function CourseContentPage() {
   return (
     <div className="min-h-screen bg-app pb-16 lg:pb-0">
       <div className="max-w-7xl mx-auto px-4 sm:px-6 lg:px-8 py-8">
-        {/* 页面头部 */}
-        <div className="mb-8">
-          <div className="flex items-center justify-between mb-4">
-            <div className="flex items-center space-x-3">
-              <div className="w-12 h-12 bg-gradient-to-r from-blue-600 to-purple-600 rounded-xl flex items-center justify-center shadow-lg">
-                <GraduationCap className="w-6 h-6 text-white" />
-              </div>
-              <div>
-                <h1 className="text-3xl font-bold">课程内容</h1>
-                <p className="text-muted-foreground">探索国土空间规划课程的核心知识点</p>
-              </div>
-            </div>
-            {/* 视图切换 */}
-            <Tabs value={viewMode} onValueChange={(v) => setViewMode(v as 'graph' | 'list')}>
-              <TabsList>
-                <TabsTrigger value="graph" className="flex items-center space-x-2">
-                  <Network className="w-4 h-4" />
-                  <span className="hidden sm:inline">知识图谱</span>
-                </TabsTrigger>
-                <TabsTrigger value="list" className="flex items-center space-x-2">
-                  <List className="w-4 h-4" />
-                  <span className="hidden sm:inline">列表视图</span>
-                </TabsTrigger>
-              </TabsList>
-            </Tabs>
-          </div>
+        {/* 视图切换 */}
+        <div className="flex justify-end mb-4">
+          <Tabs value={viewMode} onValueChange={(v) => setViewMode(v as 'graph' | 'list')}>
+            <TabsList>
+              <TabsTrigger value="graph" className="flex items-center space-x-2">
+                <Network className="w-4 h-4" />
+                <span className="hidden sm:inline">知识图谱</span>
+              </TabsTrigger>
+              <TabsTrigger value="list" className="flex items-center space-x-2">
+                <List className="w-4 h-4" />
+                <span className="hidden sm:inline">列表视图</span>
+              </TabsTrigger>
+            </TabsList>
+          </Tabs>
         </div>
 
         {/* 错误提示 */}