feat: replace nextjs-config with environment variables (#632)

* chore: remove nextjs-config

* build fix

* 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

* better .env.example

---------

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

www/app/providers.tsx

@@ -2,8 +2,8 @@
 
 import { ChakraProvider } from "@chakra-ui/react";
 import system from "./styles/theme";
+import dynamic from "next/dynamic";
 
-import { WherebyProvider } from "@whereby.com/browser-sdk/react";
 import { Toaster } from "./components/ui/toaster";
 import { NuqsAdapter } from "nuqs/adapters/next/app";
 import { QueryClientProvider } from "@tanstack/react-query";
@@ -11,6 +11,14 @@ import { queryClient } from "./lib/queryClient";
 import { AuthProvider } from "./lib/AuthProvider";
 import { SessionProvider as SessionProviderNextAuth } from "next-auth/react";
 
+const WherebyProvider = dynamic(
+  () =>
+    import("@whereby.com/browser-sdk/react").then((mod) => ({
+      default: mod.WherebyProvider,
+    })),
+  { ssr: false },
+);
+
 export function Providers({ children }: { children: React.ReactNode }) {
   return (
     <NuqsAdapter>