feat: add legal tabs and update header assets

Switch the legal page to tabbed EULA/privacy content with URL sync, update header styling, and migrate footer icons to Ant Design.

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

vite.config.ts

@@ -3,10 +3,11 @@ import { defineConfig } from "vite"
 import react from "@vitejs/plugin-react"
 import tailwindcss from "@tailwindcss/vite"
 import portChecker from "vite-plugin-port-checker"
+import { Mode, plugin as markdown } from "vite-plugin-markdown"
 
 // https://vite.dev/config/
 export default defineConfig({
-  plugins: [react(), tailwindcss(), portChecker()],
+  plugins: [react(), tailwindcss(), portChecker(), markdown({ mode: [Mode.HTML, Mode.TOC] })],
   base: "/",
   build: {
     rolldownOptions: {