flatten monorepo, migrate off Vercel

- Remove penfield (split to own repo on Forgejo)
- Move www/ contents to root, rename to wynne.rs
- Swap @astrojs/vercel for @astrojs/node, upgrade to Astro 6
- Remove auth-astro/GitHub OAuth (TinyAuth at proxy layer)
- Remove Vercel deploy webhook
- Switch to local SQLite DB (drop Turso)
- Update generate-stats.js for new build output paths

db/seed.ts

@@ -0,0 +1,14 @@
+import { db, Guestbook } from 'astro:db';
+
+export default async function seed() {
+  await db.insert(Guestbook).values([
+    {
+      id: 1,
+      name: 'test',
+      message: 'hello from dev',
+      url: null,
+      createdAt: new Date(),
+      approved: true,
+    },
+  ]);
+}