feat: redesign homepage with Radix UI and add dev environment defaults

- Replace title/tagline homepage with social profile design
- Add Radix UI Themes + icon libraries for modern UI components
- Provide sensible dev defaults for DB/secrets (no .env required)
- Add production safety checks for critical env vars
- Make optional features (cron, healthcheck) gracefully skip when unconfigured

README.md

@@ -5,6 +5,17 @@ This is the newest iteration of my personal website.
 Instead of focus on playing around or showing off blog posts, this site will focus on presentation,
 as a portfolio of what I have learned and what I can do.
 
+## Development
+
+Start the database and dev server:
+
+```bash
+pnpm db:start
+pnpm dev
+```
+
+No `.env` file needed for basic development - sensible defaults are provided. Optional features require environment variables (see `.env.example`).
+
 ## Stack
 
 - Hosted by [Vercel][vercel]