Add VPS deployment target and Ansible provisioning for lynglang.com

- deploy_site now defaults to new VPS (94.130.36.94, /var/www/lynglang);
  use --old to deploy to d.lynglang.com as before
- infra/setup_vps.yml: Ansible playbook installs nginx + certbot, obtains
  SSL cert for lynglang.com, fixes Debian buster EOL apt sources
- infra/inventory.ini and infra/templates/nginx_lynglang.conf.j2 included

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

infra/templates/nginx_lynglang.conf.j2

@@ -0,0 +1,24 @@
+server {
+    listen 80;
+    server_name {{ domain }} www.{{ domain }};
+
+    root {{ web_root }}/release/dist;
+    index index.html;
+
+    # SPA fallback
+    location / {
+        try_files $uri $uri/ /index.html;
+    }
+
+    # Distributables served directly
+    location /distributables/ {
+        try_files $uri =404;
+        autoindex on;
+    }
+
+    # Long-lived cache for hashed assets
+    location ~* \.(js|css|woff2?|ttf|eot|svg|png|jpg|ico)$ {
+        expires 1y;
+        add_header Cache-Control "public, immutable";
+    }
+}