chore: sentry and nextjs major bumps (#633)

* chore: remove nextjs-config

* build fix

* sentry update

* nextjs update

* feature flags doc

* update readme

* explicit nextjs env vars + remove feature-unrelated things and obsolete vars from config

* full config removal

* remove force-dynamic from pages

* compile fix

* restore claude-deleted tests

* no sentry backward compat

* better .env.example

* AUTHENTIK_REFRESH_TOKEN_URL not so required

* accommodate auth system to requiredLogin feature

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Co-authored-by: Igor Loskutov <igor.loskutoff@gmail.com>

www/next.config.js

@@ -1,7 +1,6 @@
 /** @type {import('next').NextConfig} */
 const nextConfig = {
   output: "standalone",
-  experimental: { esmExternals: "loose" },
   env: {
     IS_CI: process.env.IS_CI,
   },