fix(gateway): anchor config discovery and isolate env tests (#1138)

apps/gateway/src/app.module.ts

@@ -27,6 +27,7 @@ import { QueueModule } from './queue/queue.module.js';
 import { FederationModule } from './federation/federation.module.js';
 import { ThrottlerGuard, ThrottlerModule } from '@nestjs/throttler';
 import { loadConfig } from '@mosaicstack/config';
+import { resolveGatewayConfigPath } from './env.js';
 
 // Federation (step-ca client, enrollment, federation verbs) is only wired for
 // tier 'federated' — CaService hard-requires STEP_CA_* at construction, which
@@ -34,7 +35,7 @@ import { loadConfig } from '@mosaicstack/config';
 // federation profile "must not start in non-federated dev"). The gateway
 // entrypoint loads env.ts before evaluating this module so dotenv-backed tier
 // configuration is visible here.
-const federationEnabled = loadConfig().tier === 'federated';
+const federationEnabled = loadConfig(resolveGatewayConfigPath()).tier === 'federated';
 
 @Module({
   imports: [