feat: AI分析单页展示 + 主题切换 + 移动端适配

- AI分析页改为直接展示最新报告，历史存数据库
- 新增浅色/深色/系统自动主题切换
- 市场看板、AI分析页适配主题变量
- 移动端表格可滑动、按钮自动换行
- Mermaid图表支持
- Markdown表格渲染支持(remark-gfm)

src/lib/ai-analysis-api.ts

@@ -17,6 +17,13 @@ export interface AiReport {
   created_at: string;
 }
 
+export async function fetchAiLatestReport(): Promise<AiReport> {
+  const resp = await fetch(`${API_BASE}/api/ai-analysis/latest`);
+  if (!resp.ok) throw new Error(`请求失败 (${resp.status})`);
+  const result = await resp.json();
+  return result.data;
+}
+
 export async function fetchAiReports(): Promise<AiReport[]> {
   const resp = await fetch(`${API_BASE}/api/ai-analysis`);
   if (!resp.ok) throw new Error(`请求失败 (${resp.status})`);

src/lib/use-theme.ts

@@ -0,0 +1,56 @@
+import { useState, useEffect, useCallback } from "react";
+
+type Theme = "light" | "dark" | "system";
+
+function getSystemTheme(): "light" | "dark" {
+  if (typeof window === "undefined") return "light";
+  return window.matchMedia("(prefers-color-scheme: dark)").matches ? "dark" : "light";
+}
+
+function getResolvedTheme(theme: Theme): "light" | "dark" {
+  return theme === "system" ? getSystemTheme() : theme;
+}
+
+function applyTheme(resolved: "light" | "dark") {
+  const root = document.documentElement;
+  root.classList.remove("light", "dark");
+  root.classList.add(resolved);
+  root.setAttribute("data-theme", resolved);
+}
+
+export function useTheme() {
+  const [theme, setThemeState] = useState<Theme>(() => {
+    if (typeof window === "undefined") return "system";
+    return (localStorage.getItem("theme") as Theme) || "system";
+  });
+
+  const [resolved, setResolved] = useState<"light" | "dark">(() => getResolvedTheme(theme));
+
+  const setTheme = useCallback((newTheme: Theme) => {
+    setThemeState(newTheme);
+    localStorage.setItem("theme", newTheme);
+    const r = getResolvedTheme(newTheme);
+    setResolved(r);
+    applyTheme(r);
+  }, []);
+
+  // 初始应用
+  useEffect(() => {
+    applyTheme(resolved);
+  }, []);
+
+  // 监听系统主题变化
+  useEffect(() => {
+    if (theme !== "system") return;
+    const mq = window.matchMedia("(prefers-color-scheme: dark)");
+    const handler = () => {
+      const r = getSystemTheme();
+      setResolved(r);
+      applyTheme(r);
+    };
+    mq.addEventListener("change", handler);
+    return () => mq.removeEventListener("change", handler);
+  }, [theme]);
+
+  return { theme, resolved, setTheme };
+}