docker: overhaul container image

.github/docker/Caddyfile

@@ -0,0 +1,30 @@
+:8080 {
+	root * /var/www/pterodactyl/public/
+	file_server
+
+	header {
+		-Server
+		-X-Powered-By
+		Referrer-Policy "same-origin"
+		X-Frame-Options "deny"
+		X-XSS-Protection "1; mode=block"
+		X-Content-Type-Options "nosniff"
+	}
+
+	encode gzip zstd
+
+	php_fastcgi 127.0.0.1:9000 {
+		trusted_proxies 172.20.0.0/16
+	}
+
+	@startsWithDot {
+		path \/\.
+		not path .well-known
+	}
+	rewrite @startsWithDot /index.php{uri}
+
+	@phpRewrite {
+		not file favicon.ico
+	}
+	try_files @phpRewrite {path} {path}/ /index.php?{query}
+}