feat(backend): add GemeindeController for LT congregation CRUD

Fills the plan's known gap where Gemeinde existed only as a Prisma model.
GemeindeModule exposes Leitungsteam-only create/list/get/update/delete
under /api/gemeinde, each mutation captured into the sync log like the
other feature services. Unique-name-per-KC violations surface as 409.
Docs (plan + backend README) updated to drop the gap and next-step item.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/app.module.ts

@@ -5,6 +5,7 @@ import { join } from 'path';
 import { PrismaModule } from './prisma/prisma.module';
 import { AuthModule } from './auth/auth.module';
 import { KcModule } from './kc/kc.module';
+import { GemeindeModule } from './gemeinde/gemeinde.module';
 import { WahlModule } from './wahl/wahl.module';
 import { FilesModule } from './files/files.module';
 import { ChatModule } from './chat/chat.module';
@@ -23,6 +24,7 @@ import { SyncModule } from './sync/sync.module';
     SyncModule,
     AuthModule,
     KcModule,
+    GemeindeModule,
     WahlModule,
     FilesModule,
     ChatModule,

src/gemeinde/dto/create-gemeinde.dto.ts

@@ -0,0 +1,11 @@
+import { IsNotEmpty, IsString } from 'class-validator';
+
+export class CreateGemeindeDto {
+  @IsString()
+  @IsNotEmpty()
+  kcId!: string;
+
+  @IsString()
+  @IsNotEmpty()
+  name!: string;
+}

src/gemeinde/dto/update-gemeinde.dto.ts

@@ -0,0 +1,7 @@
+import { IsNotEmpty, IsString } from 'class-validator';
+
+export class UpdateGemeindeDto {
+  @IsString()
+  @IsNotEmpty()
+  name!: string;
+}

src/gemeinde/gemeinde.controller.ts

@@ -0,0 +1,53 @@
+import {
+  Body,
+  Controller,
+  Delete,
+  Get,
+  Param,
+  Patch,
+  Post,
+  Query,
+  UseGuards,
+} from '@nestjs/common';
+import { AuthGuard } from '@nestjs/passport';
+import { GemeindeService } from './gemeinde.service';
+import { CreateGemeindeDto } from './dto/create-gemeinde.dto';
+import { UpdateGemeindeDto } from './dto/update-gemeinde.dto';
+import { Roles } from '../common/roles.decorator';
+import { RolesGuard } from '../common/roles.guard';
+import { Role } from '../common/role.enum';
+
+/// Gemeinde (congregation) management. Reserved for the Leitungsteam, which is
+/// global across all KCs (see RolesGuard); Gemeinde Verantwortliche/Teamer
+/// learn their own Gemeinde from their Membership, not from this endpoint.
+@Controller('gemeinde')
+@UseGuards(AuthGuard('authentik'), RolesGuard)
+@Roles(Role.LEITUNGSTEAM)
+export class GemeindeController {
+  constructor(private readonly gemeinde: GemeindeService) {}
+
+  @Post()
+  create(@Body() dto: CreateGemeindeDto) {
+    return this.gemeinde.create(dto.kcId, dto.name);
+  }
+
+  @Get()
+  list(@Query('kcId') kcId: string) {
+    return this.gemeinde.list(kcId);
+  }
+
+  @Get(':id')
+  get(@Param('id') id: string) {
+    return this.gemeinde.get(id);
+  }
+
+  @Patch(':id')
+  update(@Param('id') id: string, @Body() dto: UpdateGemeindeDto) {
+    return this.gemeinde.update(id, dto.name);
+  }
+
+  @Delete(':id')
+  remove(@Param('id') id: string) {
+    return this.gemeinde.remove(id);
+  }
+}

src/gemeinde/gemeinde.module.ts

@@ -0,0 +1,9 @@
+import { Module } from '@nestjs/common';
+import { GemeindeService } from './gemeinde.service';
+import { GemeindeController } from './gemeinde.controller';
+
+@Module({
+  providers: [GemeindeService],
+  controllers: [GemeindeController],
+})
+export class GemeindeModule {}

src/gemeinde/gemeinde.service.ts

@@ -0,0 +1,81 @@
+import {
+  ConflictException,
+  Injectable,
+  NotFoundException,
+} from '@nestjs/common';
+import { Prisma, SyncOperation } from '@prisma/client';
+import { PrismaClient } from '../prisma/prisma.module';
+import { SyncService } from '../sync/sync.service';
+
+/// CRUD for Gemeinden (congregations) within a KC. Creating/renaming/deleting
+/// is Leitungsteam-only (see GemeindeController); other team roles may list
+/// and read the Gemeinden of their KC for onboarding/assignment UIs.
+@Injectable()
+export class GemeindeService {
+  constructor(
+    private readonly prisma: PrismaClient,
+    private readonly sync: SyncService,
+  ) {}
+
+  async create(kcId: string, name: string) {
+    const kc = await this.prisma.kc.findUnique({ where: { id: kcId } });
+    if (!kc) {
+      throw new NotFoundException('KC not found');
+    }
+    try {
+      const gemeinde = await this.prisma.gemeinde.create({ data: { kcId, name } });
+      await this.sync.capture('Gemeinde', SyncOperation.CREATE, gemeinde.id, gemeinde);
+      return gemeinde;
+    } catch (err) {
+      if (
+        err instanceof Prisma.PrismaClientKnownRequestError &&
+        err.code === 'P2002'
+      ) {
+        throw new ConflictException('A Gemeinde with this name already exists in this KC');
+      }
+      throw err;
+    }
+  }
+
+  list(kcId: string) {
+    return this.prisma.gemeinde.findMany({
+      where: { kcId },
+      orderBy: { name: 'asc' },
+    });
+  }
+
+  async get(id: string) {
+    const gemeinde = await this.prisma.gemeinde.findUnique({ where: { id } });
+    if (!gemeinde) {
+      throw new NotFoundException('Gemeinde not found');
+    }
+    return gemeinde;
+  }
+
+  async update(id: string, name: string) {
+    await this.get(id);
+    try {
+      const gemeinde = await this.prisma.gemeinde.update({
+        where: { id },
+        data: { name },
+      });
+      await this.sync.capture('Gemeinde', SyncOperation.UPDATE, gemeinde.id, gemeinde);
+      return gemeinde;
+    } catch (err) {
+      if (
+        err instanceof Prisma.PrismaClientKnownRequestError &&
+        err.code === 'P2002'
+      ) {
+        throw new ConflictException('A Gemeinde with this name already exists in this KC');
+      }
+      throw err;
+    }
+  }
+
+  async remove(id: string) {
+    await this.get(id);
+    const gemeinde = await this.prisma.gemeinde.delete({ where: { id } });
+    await this.sync.capture('Gemeinde', SyncOperation.DELETE, gemeinde.id, gemeinde);
+    return gemeinde;
+  }
+}