feat(server): add global encryption module (AES-256-GCM) (#2400)

Provides an injectable EncryptionService that encrypts/decrypts strings
with AES-256-GCM using a key derived from APP_SECRET with domain
separation.

apps/server/src/app.module.ts

@@ -27,6 +27,7 @@ import { LoggerModule } from './common/logger/logger.module';
 import { ClsModule } from 'nestjs-cls';
 import { NoopAuditModule } from './integrations/audit/audit.module';
 import { ThrottleModule } from './integrations/throttle/throttle.module';
+import { EncryptionModule } from './integrations/encryption/encryption.module';
 
 const enterpriseModules = [];
 try {
@@ -53,6 +54,7 @@ try {
     CoreModule,
     DatabaseModule,
     EnvironmentModule,
+    EncryptionModule,
     RedisModule.forRootAsync({
       useClass: RedisConfigService,
     }),