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>

nginx/default.conf

@@ -0,0 +1,32 @@
+server {
+    listen 80;
+    listen [::]:80;
+    server_name playground.schwenk.online;
+
+    root /usr/share/nginx/html;
+    index index.html;
+
+    include /etc/nginx/conf.d/security-headers.conf;
+
+    gzip on;
+    gzip_vary on;
+    gzip_proxied any;
+    gzip_comp_level 6;
+    gzip_types text/plain text/css text/xml application/json application/javascript application/xml+rss application/atom+xml image/svg+xml;
+
+    location ~* \.(jpg|jpeg|png|gif|ico|css|js|svg|webp)$ {
+        expires 1y;
+        add_header Cache-Control "public, no-transform";
+    }
+
+    location / {
+        try_files $uri $uri/ =404;
+    }
+
+    location ~ /\. {
+        deny all;
+        return 404;
+        access_log off;
+        log_not_found off;
+    }
+}

nginx/security-headers.conf

@@ -0,0 +1,8 @@
+# Security headers for playground.schwenk.online (plain static HTML).
+
+add_header Strict-Transport-Security "max-age=63072000; includeSubDomains" always;
+add_header X-Frame-Options "SAMEORIGIN" always;
+add_header X-Content-Type-Options "nosniff" always;
+add_header Referrer-Policy "strict-origin-when-cross-origin" always;
+add_header Permissions-Policy "geolocation=(), microphone=(), camera=()" always;
+add_header Content-Security-Policy "default-src 'self'; style-src 'self' 'unsafe-inline'; img-src 'self' data: https:; base-uri 'self'; form-action 'self'; object-src 'none'" always;