ci: update compose.yml for prod deployment

- Add Nginx as a reverse proxy
- Add cert-selfsign.sh for generating self-signed certificates
- Add certbot-issue.sh for Let's Encrypt certificate issuance and renewal
- Add cron-install.sh and cron-uninstall.sh for system cron management
- Add .env.example as an environment variable template

nginx/default.conf.example

@@ -0,0 +1,38 @@
+upstream pyrigs {
+    server pyrigs:8000;
+}
+
+server {
+    listen 80;
+    server_name _;
+
+    # Let's Encrypt HTTP-01
+    location /.well-known/acme-challenge/ {
+        root /var/www/certbot;
+    }
+
+    location / {
+        return 301 https://$host$request_uri;
+    }
+}
+
+server {
+    listen 443 ssl;
+    http2 on;
+    server_name _;
+
+    ssl_certificate     /etc/nginx/certs/fullchain.pem;
+    ssl_certificate_key /etc/nginx/certs/privkey.pem;
+    ssl_protocols       TLSv1.2 TLSv1.3;
+
+    client_max_body_size 20m;
+
+    location / {
+        proxy_pass http://pyrigs;
+        proxy_set_header Host              $host;
+        proxy_set_header X-Real-IP         $remote_addr;
+        proxy_set_header X-Forwarded-For   $proxy_add_x_forwarded_for;
+        proxy_set_header X-Forwarded-Proto https;
+        proxy_redirect off;
+    }
+}