Cloudflare prep and headers fix

.nvmrc

@@ -0,0 +1 @@
+22

public/_headers

@@ -0,0 +1,14 @@
+/*
+  X-Frame-Options: SAMEORIGIN
+  X-XSS-Protection: 1; mode=block
+  X-Content-Type-Options: nosniff
+  X-DNS-Prefetch-Control: on
+  X-Download-Options: noopen
+  Cross-Origin-Opener-Policy: unsafe-none
+  Cross-Origin-Resource-Policy: same-origin
+  Cross-Origin-Embedder-Policy: unsafe-none
+  Strict-Transport-Security: max-age=31536000; includeSubDomains
+  Referrer-Policy: strict-origin-when-cross-origin
+  Access-Control-Allow-Methods: GET
+  Content-Security-Policy: base-uri 'self'; font-src 'self' data:; form-action 'self'; frame-ancestors 'self'; img-src 'self' https://*.add-to-calendar-pro.com https://add-to-calendar-pro.com https://*.caldn.net data:; object-src 'none'; script-src-attr 'self'; script-src 'self' 'unsafe-inline' https://*.add-to-calendar-pro.com https://add-to-calendar-pro.com; style-src 'self' 'unsafe-inline' https://*.add-to-calendar-pro.com https://add-to-calendar-pro.com https://cdn.jsdelivr.net; frame-src 'self'; upgrade-insecure-requests;
+  Permissions-Policy: geolocation=(),midi=(),microphone=(),camera=(),gyroscope=(*),encrypted-media=(*),payment=()