feat: playground static site with cursor webhook deploy

Scaffold nginx + deploy-hook stack for playground.schwenk.online,
Gitea cursor workflow, directory-based public/ content, and boka
bootstrap via git clone.

Co-authored-by: Cursor <cursoragent@cursor.com>

deploy-hook/Dockerfile

@@ -0,0 +1,9 @@
+FROM almir/webhook:latest
+
+USER root
+RUN apk add --no-cache git bash gettext-envsubst
+COPY entrypoint.sh /entrypoint.sh
+RUN chmod +x /entrypoint.sh
+
+USER webhook
+ENTRYPOINT ["/entrypoint.sh"]