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/package.json

@@ -16,11 +16,13 @@
     "@repo/config": "workspace:*",
     "@repo/ui": "workspace:*",
     "framer-motion": "^11.0.0",
+    "gray-matter": "^4.0.3",
     "lucide-react": "^0.350.0",
     "next": "^15.1.3",
+    "next-mdx-remote": "^6.0.0",
     "next-themes": "^0.4.6",
-    "react": "^18.2.0",
-    "react-dom": "^18.2.0",
+    "react": "^19.2.4",
+    "react-dom": "^19.2.4",
     "react-icons": "^5.5.0",
     "resend": "^4.0.0",
     "zod": "^3.22.4"
@@ -30,8 +32,8 @@
     "@playwright/test": "^1.57.0",
     "@tailwindcss/typography": "^0.5.19",
     "@types/node": "^20.0.0",
-    "@types/react": "^18.0.0",
-    "@types/react-dom": "^18.0.0",
+    "@types/react": "^19.2.14",
+    "@types/react-dom": "^19.2.3",
     "autoprefixer": "^10.0.1",
     "eslint": "^8",
     "eslint-config-next": "^15.1.3",