feat: complete v0.3 reading and discovery experience

app/components/markdown.tsx

@@ -0,0 +1,8 @@
+import ReactMarkdown from "react-markdown";
+import rehypeHighlight from "rehype-highlight";
+import remarkGfm from "remark-gfm";
+
+/** Raw HTML is intentionally not enabled, so Memos content cannot inject script or markup. */
+export function Markdown({ content, compact = false }: { content: string; compact?: boolean }) {
+  return <div className={`markdown${compact ? " markdown-compact" : ""}`}><ReactMarkdown remarkPlugins={[remarkGfm]} rehypePlugins={[rehypeHighlight]}>{content}</ReactMarkdown></div>;
+}