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/(app)/layout.tsx

@@ -1,5 +1,5 @@
 import { Container, Flex, Link } from "@chakra-ui/react";
-import { getConfig } from "../lib/edgeConfig";
+import { featureEnabled } from "../lib/features";
 import NextLink from "next/link";
 import Image from "next/image";
 import UserInfo from "../(auth)/userInfo";
@@ -11,8 +11,6 @@ export default async function AppLayout({
 }: {
   children: React.ReactNode;
 }) {
-  const config = await getConfig();
-  const { requireLogin, privacy, browse, rooms } = config.features;
   return (
     <Container
       minW="100vw"
@@ -58,7 +56,7 @@ export default async function AppLayout({
           >
             Create
           </Link>
-          {browse ? (
+          {featureEnabled("browse") ? (
             <>
               &nbsp;·&nbsp;
               <Link href="/browse" as={NextLink} className="font-light px-2">
@@ -68,7 +66,7 @@ export default async function AppLayout({
           ) : (
             <></>
           )}
-          {rooms ? (
+          {featureEnabled("rooms") ? (
             <>
               &nbsp;·&nbsp;
               <Link href="/rooms" as={NextLink} className="font-light px-2">
@@ -78,7 +76,7 @@ export default async function AppLayout({
           ) : (
             <></>
           )}
-          {requireLogin ? (
+          {featureEnabled("requireLogin") ? (
             <>
               &nbsp;·&nbsp;
               <UserInfo />