Migrate blog from hardcoded TSX posts to MDX with auto-population

- Add gray-matter + next-mdx-remote for MDX rendering
- Create content/blog/ with .mdx files and frontmatter
- Add dynamic [slug] route and blog utility (src/lib/blog.ts)
- Blog index auto-populates from MDX files, sorted newest first
- Upgrade React to 19 for next-mdx-remote v6 compatibility
- Convert existing posts: website-relaunch, smirk-wallet, bauhaus-echo, crypto-checkout

apps/web/src/lib/blog.ts

@@ -0,0 +1,64 @@
+import fs from "fs";
+import path from "path";
+import matter from "gray-matter";
+
+const CONTENT_DIR = path.join(process.cwd(), "content", "blog");
+
+export type PostMeta = {
+  slug: string;
+  title: string;
+  date: string;
+  excerpt: string;
+  draft: boolean;
+};
+
+export type Post = PostMeta & {
+  content: string;
+};
+
+export function getAllPosts(): PostMeta[] {
+  if (!fs.existsSync(CONTENT_DIR)) return [];
+
+  return fs
+    .readdirSync(CONTENT_DIR)
+    .filter((f) => f.endsWith(".mdx"))
+    .map((filename) => {
+      const slug = filename.replace(/\.mdx$/, "");
+      const raw = fs.readFileSync(path.join(CONTENT_DIR, filename), "utf-8");
+      const { data } = matter(raw);
+      return {
+        slug,
+        title: data.title ?? slug,
+        date: data.date ?? "",
+        excerpt: data.excerpt ?? "",
+        draft: data.draft === true,
+      };
+    })
+    .filter((p) => !p.draft)
+    .sort((a, b) => (a.date > b.date ? -1 : 1));
+}
+
+export function getPost(slug: string): Post | null {
+  const filePath = path.join(CONTENT_DIR, `${slug}.mdx`);
+  if (!fs.existsSync(filePath)) return null;
+
+  const raw = fs.readFileSync(filePath, "utf-8");
+  const { data, content } = matter(raw);
+  return {
+    slug,
+    title: data.title ?? slug,
+    date: data.date ?? "",
+    excerpt: data.excerpt ?? "",
+    draft: data.draft === true,
+    content,
+  };
+}
+
+export function getAllSlugs(): string[] {
+  if (!fs.existsSync(CONTENT_DIR)) return [];
+
+  return fs
+    .readdirSync(CONTENT_DIR)
+    .filter((f) => f.endsWith(".mdx"))
+    .map((f) => f.replace(/\.mdx$/, ""));
+}