feat(backend): implement Relais module and relation with Gestionnaire (Ticket #94)

- Create Relais entity
- Create Relais module, controller, service with CRUD
- Update Users entity with ManyToOne relation to Relais
- Update GestionnairesService to handle relaisId

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/src/routes/relais/relais.module.ts

@@ -0,0 +1,17 @@
+import { Module } from '@nestjs/common';
+import { TypeOrmModule } from '@nestjs/typeorm';
+import { RelaisService } from './relais.service';
+import { RelaisController } from './relais.controller';
+import { Relais } from 'src/entities/relais.entity';
+import { AuthModule } from 'src/routes/auth/auth.module';
+
+@Module({
+  imports: [
+    TypeOrmModule.forFeature([Relais]),
+    AuthModule,
+  ],
+  controllers: [RelaisController],
+  providers: [RelaisService],
+  exports: [RelaisService],
+})
+export class RelaisModule {}