fix: move gray-matter and reading-time to dependencies

These packages are needed at build time, not just dev time.
Netlify sets NODE_ENV=production which skips devDependencies.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: cj-vana

package.json

@@ -33,9 +33,7 @@
     "remark-gfm": "^4.0.0",
     "tailwindcss": "^4",
     "tsx": "^4.21.0",
-    "typescript": "^5"
-  },
-  "devDependencies": {
+    "typescript": "^5",
     "gray-matter": "^4.0.3",
     "reading-time": "^1.5.0"
   }