feat: 新增题材页面（列表 + 详情）

- 主页增加「题材热点」入口，跳转题材列表页
- 题材列表页：展示全部题材，支持按涨幅/强度/热度/成交额排序
- 题材详情页：简介、热点事件、相关新闻、板块涨跌统计、全部相关股票（含入选理由默认展开）
- 后端逆向封装东方财富题材接口 getThemeList/getDetail/getStockList，含交易时段感知缓存

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

src/routes/index.tsx

@@ -10,7 +10,7 @@ import { Dialog, DialogContent, DialogHeader, DialogTitle, DialogTrigger } from
 import { AlertDialog, AlertDialogAction, AlertDialogCancel, AlertDialogContent, AlertDialogDescription, AlertDialogFooter, AlertDialogHeader, AlertDialogTitle } from "@/components/ui/alert-dialog";
 import { Label } from "@/components/ui/label";
 import { Textarea } from "@/components/ui/textarea";
-import { Search, Plus, Share2, Trash2, TrendingUp, Loader2 } from "lucide-react";
+import { Search, Plus, Share2, Trash2, TrendingUp, Loader2, Flame } from "lucide-react";
 import { toast } from "sonner";
 
 export const Route = createFileRoute("/")({
@@ -211,12 +211,20 @@ function Index() {
             A股走势追踪
           </h1>
           <p className="text-sm md:text-base text-muted-foreground">创建股票集合，分享历史走势</p>
-          <Link to="/sectors">
-            <Button variant="outline" size="sm" className="mt-3 gap-1.5 text-xs">
-              <TrendingUp className="h-3.5 w-3.5" />
-              板块资金流向
-            </Button>
-          </Link>
+          <div className="mt-3 flex items-center justify-center gap-2">
+            <Link to="/sectors">
+              <Button variant="outline" size="sm" className="gap-1.5 text-xs">
+                <TrendingUp className="h-3.5 w-3.5" />
+                板块资金流向
+              </Button>
+            </Link>
+            <Link to="/themes">
+              <Button variant="outline" size="sm" className="gap-1.5 text-xs">
+                <Flame className="h-3.5 w-3.5" />
+                题材热点
+              </Button>
+            </Link>
+          </div>
         </div>
 
         <Card className="mb-6 md:mb-8 shadow-lg">