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/lib/theme-api.ts

@@ -0,0 +1,160 @@
+// 题材数据获取工具：通过 Python 后端代理调用东方财富题材接口
+import { getApiBaseUrl } from "@/lib/api-client";
+
+/* ── 题材列表 ── */
+
+export interface ThemeItem {
+  themeCode: string;
+  themeName: string;
+  securityName: string; // 领涨股名称
+  securityCode: string; // 领涨股代码
+  codeWithSuffix: string;
+  hotRank: number; // 热度排名
+  f3: number | null; // 领涨股涨幅
+  bf3: number | null; // 题材涨幅
+  hotValue: number; // 热度值
+  hotValueUpLimit: number; // 热度上限
+  strengthValue: number | null; // 强度值
+  fex5: number | null; // 成交额
+  fex3: number | null;
+  label: string | null; // 标签（如"超级爆点"）
+}
+
+export type ThemeSortField = 1 | 3 | 4 | 5; // 1=涨幅 3=强度 4=热度排名 5=成交额
+
+export interface ThemeListResponse {
+  data: ThemeItem[];
+  count: number;
+  sort_field: number;
+  asc: boolean;
+}
+
+/**
+ * 获取全部题材列表
+ * @param sortField 1=涨幅 3=强度 4=热度排名 5=成交额
+ * @param asc true=升序
+ */
+export async function fetchThemes(sortField: ThemeSortField = 1, asc: boolean = false): Promise<ThemeItem[]> {
+  const baseUrl = getApiBaseUrl();
+  const url = `${baseUrl}/api/themes?sort_field=${sortField}&asc=${asc}`;
+
+  try {
+    const resp = await fetch(url, { method: "GET", cache: "no-store" });
+    if (!resp.ok) return [];
+    const result: ThemeListResponse = await resp.json();
+    return result.data || [];
+  } catch (err) {
+    console.error("[theme-api] 获取题材列表失败:", err);
+    return [];
+  }
+}
+
+/* ── 题材详情 ── */
+
+export interface ThemeHotEvent {
+  newsTitle: string | null;
+  newsSummary: string | null;
+  newsMediaName: string | null;
+  newsPublishTimeFormat: string | null;
+  newsCode: string | null;
+}
+
+export interface ThemeNews {
+  newsCode: string;
+  newsTitle: string;
+  newsMediaName: string;
+  newsPublishTime: number | null;
+}
+
+export interface ThemeBaseInfo {
+  themeCode: string;
+  themeName: string;
+  introduction: string;
+  explainImgUrl: string | null;
+  themeLevel: number;
+  isShowRank: number;
+}
+
+export interface ThemeDetail {
+  baseInfo: ThemeBaseInfo;
+  hotEvent: ThemeHotEvent | null;
+  eventHistory: ThemeNews[];
+  topicId: string | null;
+}
+
+/**
+ * 获取题材详情（简介 + 热点事件 + 相关新闻）
+ */
+export async function fetchThemeDetail(themeCode: string): Promise<ThemeDetail | null> {
+  const baseUrl = getApiBaseUrl();
+  const url = `${baseUrl}/api/themes/${themeCode}/detail`;
+
+  try {
+    const resp = await fetch(url, { method: "GET", cache: "no-store" });
+    if (!resp.ok) return null;
+    const result = await resp.json();
+    return result.data || null;
+  } catch (err) {
+    console.error("[theme-api] 获取题材详情失败:", err);
+    return null;
+  }
+}
+
+/* ── 题材相关股票 ── */
+
+export interface ThemeStockKeyword {
+  keywordCode: string;
+  keyword: string;
+  introduction: string;
+}
+
+export interface ThemeStock {
+  securityName: string;
+  securityCode: string;
+  codeSuffix: string;
+  f2: number; // 现价
+  f3: number; // 涨跌幅%
+  f5: number; // 成交量
+  f6: number; // 成交额
+  f8: number; // 换手率%
+  f20: number; // 总市值
+  f21: number; // 流通市值
+  f62: number; // 主力净流入
+  f100: string; // 所属行业
+  f265: string; // 板块代码
+  label: string | null; // 涨停标签
+  rank: number;
+  dragonStockLabel: number;
+  keywordList: ThemeStockKeyword[]; // 入选理由
+}
+
+export interface ThemeStatistic {
+  f3: number | null; // 板块涨幅
+  f104: number | null; // 上涨家数
+  f105: number | null; // 下跌家数
+  f106: number | null; // 平盘家数
+  fex5: number | null; // 板块成交额
+}
+
+export interface ThemeStocksResponse {
+  data: ThemeStock[];
+  statistic: ThemeStatistic;
+  total: number;
+}
+
+/**
+ * 获取题材下全部相关股票
+ */
+export async function fetchThemeStocks(themeCode: string): Promise<ThemeStocksResponse | null> {
+  const baseUrl = getApiBaseUrl();
+  const url = `${baseUrl}/api/themes/${themeCode}/stocks`;
+
+  try {
+    const resp = await fetch(url, { method: "GET", cache: "no-store" });
+    if (!resp.ok) return null;
+    return await resp.json();
+  } catch (err) {
+    console.error("[theme-api] 获取题材股票失败:", err);
+    return null;
+  }
+}