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)/transcripts/new/page.tsx

@@ -9,7 +9,6 @@ import { useRouter } from "next/navigation";
 import useCreateTranscript from "../createTranscript";
 import SelectSearch from "react-select-search";
 import { supportedLanguages } from "../../../supportedLanguages";
-import { featureEnabled } from "../../../domainContext";
 import {
   Flex,
   Box,
@@ -21,10 +20,9 @@ import {
   Spacer,
 } from "@chakra-ui/react";
 import { useAuth } from "../../../lib/AuthProvider";
-import type { components } from "../../../reflector-api";
+import { featureEnabled } from "../../../lib/features";
 
 const TranscriptCreate = () => {
-  const isClient = typeof window !== "undefined";
   const router = useRouter();
   const auth = useAuth();
   const isAuthenticated = auth.status === "authenticated";
@@ -176,7 +174,7 @@ const TranscriptCreate = () => {
                     placeholder="Choose your language"
                   />
                 </Box>
-                {isClient && !loading ? (
+                {!loading ? (
                   permissionOk ? (
                     <Spacer />
                   ) : permissionDenied ? (