feat: add Astro source code

- Proper Astro project structure
- Nav, hero, GPG badge, status indicator
- Inter + JetBrains Mono fonts

astro.config.mjs

@@ -0,0 +1,5 @@
+// @ts-check
+import { defineConfig } from 'astro/config';
+
+// https://astro.build/config
+export default defineConfig({});