feat(api): add GroupsModule with GET /groups endpoint

Implements TDD-driven GroupsService and GroupsController with full unit test coverage. GET /groups returns all groups ordered by name, selecting id, name, platform, platformId, isActive, and accountId fields.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/api/src/modules/groups/groups.controller.spec.ts

@@ -0,0 +1,26 @@
+import { Test, TestingModule } from '@nestjs/testing';
+import { GroupsController } from './groups.controller';
+import { GroupsService } from './groups.service';
+
+const mockGroups = [
+  { id: 'grp_1', name: 'Alpha', platform: 'whatsapp', platformId: '111@g.us', isActive: true, accountId: 'acc_1' },
+];
+const mockService = { list: jest.fn().mockResolvedValue(mockGroups) };
+
+describe('GroupsController', () => {
+  let controller: GroupsController;
+
+  beforeEach(async () => {
+    const module: TestingModule = await Test.createTestingModule({
+      controllers: [GroupsController],
+      providers: [{ provide: GroupsService, useValue: mockService }],
+    }).compile();
+    controller = module.get<GroupsController>(GroupsController);
+  });
+
+  it('returns groups from service', async () => {
+    const result = await controller.list();
+    expect(result).toEqual(mockGroups);
+    expect(mockService.list).toHaveBeenCalled();
+  });
+});

apps/api/src/modules/groups/groups.controller.ts

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+import { Controller, Get } from '@nestjs/common';
+import { GroupsService } from './groups.service';
+
+@Controller('groups')
+export class GroupsController {
+  constructor(private readonly groupsService: GroupsService) {}
+
+  @Get()
+  list() {
+    return this.groupsService.list();
+  }
+}

apps/api/src/modules/groups/groups.module.ts

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+import { Module } from '@nestjs/common';
+import { GroupsController } from './groups.controller';
+import { GroupsService } from './groups.service';
+
+@Module({
+  controllers: [GroupsController],
+  providers: [GroupsService],
+})
+export class GroupsModule {}

apps/api/src/modules/groups/groups.service.spec.ts

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+import { Test, TestingModule } from '@nestjs/testing';
+import { GroupsService } from './groups.service';
+import { PrismaService } from '../../prisma/prisma.service';
+
+const mockGroups = [
+  { id: 'grp_1', name: 'Alpha', platform: 'whatsapp', platformId: '111@g.us', isActive: true, accountId: 'acc_1' },
+  { id: 'grp_2', name: 'Beta', platform: 'whatsapp', platformId: '222@g.us', isActive: true, accountId: null },
+];
+
+describe('GroupsService', () => {
+  let service: GroupsService;
+  const mockPrisma = { group: { findMany: jest.fn().mockResolvedValue(mockGroups) } };
+
+  beforeEach(async () => {
+    const module: TestingModule = await Test.createTestingModule({
+      providers: [
+        GroupsService,
+        { provide: PrismaService, useValue: mockPrisma },
+      ],
+    }).compile();
+    service = module.get<GroupsService>(GroupsService);
+  });
+
+  it('returns all groups ordered by name', async () => {
+    const result = await service.list();
+    expect(result).toHaveLength(2);
+    expect(result[0].name).toBe('Alpha');
+    expect(mockPrisma.group.findMany).toHaveBeenCalledWith({
+      orderBy: { name: 'asc' },
+      select: { id: true, name: true, platform: true, platformId: true, isActive: true, accountId: true },
+    });
+  });
+});

apps/api/src/modules/groups/groups.service.ts

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+import { Injectable } from '@nestjs/common';
+import { PrismaService } from '../../prisma/prisma.service';
+
+@Injectable()
+export class GroupsService {
+  constructor(private readonly prisma: PrismaService) {}
+
+  list() {
+    return this.prisma.group.findMany({
+      orderBy: { name: 'asc' },
+      select: { id: true, name: true, platform: true, platformId: true, isActive: true, accountId: true },
+    });
+  }
+}