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/middleware.ts

@@ -1,5 +1,5 @@
 import { withAuth } from "next-auth/middleware";
-import { getConfig } from "./app/lib/edgeConfig";
+import { featureEnabled } from "./app/lib/features";
 import { NextResponse } from "next/server";
 import { PROTECTED_PAGES } from "./app/lib/auth";
 
@@ -19,13 +19,12 @@ export const config = {
 
 export default withAuth(
   async function middleware(request) {
-    const config = await getConfig();
     const pathname = request.nextUrl.pathname;
 
     // feature-flags protected paths
     if (
-      (!config.features.browse && pathname.startsWith("/browse")) ||
-      (!config.features.rooms && pathname.startsWith("/rooms"))
+      (!featureEnabled("browse") && pathname.startsWith("/browse")) ||
+      (!featureEnabled("rooms") && pathname.startsWith("/rooms"))
     ) {
       return NextResponse.redirect(request.nextUrl.origin);
     }
@@ -33,10 +32,8 @@ export default withAuth(
   {
     callbacks: {
       async authorized({ req, token }) {
-        const config = await getConfig();
-
         if (
-          config.features.requireLogin &&
+          featureEnabled("requireLogin") &&
           PROTECTED_PAGES.test(req.nextUrl.pathname)
         ) {
           return !!token;