feat: switch to Astro DB for guestbook

- Add @astrojs/db integration
- Define Guestbook schema in db/config.ts
- Add seed data for development
- Update db.ts to use astro:db
- Add guestbook section to homepage with form
- Update env vars to use ASTRO_DB_REMOTE_URL

apps/blog/src/styles/global.css

@@ -46,3 +46,48 @@ summary::-webkit-details-marker {
 details pre {
   margin: 0;
 }
+
+#guestbook-form {
+  display: flex;
+  flex-direction: column;
+  gap: 0.5rem;
+  padding-left: 1rem;
+  margin-top: 0.5rem;
+}
+
+#guestbook-form input,
+#guestbook-form textarea {
+  font-family: monospace;
+  font-size: 1rem;
+  padding: 0.25rem;
+  border: 1px solid #888;
+  background: transparent;
+  color: inherit;
+}
+
+#guestbook-form textarea {
+  min-height: 3rem;
+  resize: vertical;
+}
+
+#guestbook-form button {
+  font-family: monospace;
+  font-size: 1rem;
+  padding: 0.25rem 0.5rem;
+  cursor: pointer;
+  background: transparent;
+  border: 1px solid #888;
+  color: inherit;
+  align-self: flex-start;
+}
+
+#guestbook-form button:hover {
+  background: #888;
+  color: #000;
+}
+
+#guestbook-status {
+  padding-left: 1rem;
+  color: #888;
+  font-family: monospace;
+}