Add issue attachments

- IssueAttachment link table (issue <-> file) + migration
- GET/POST /issues/:issueId/attachments, DELETE .../attachments/:fileId
- Only own uploaded files can be attached; attach is idempotent
- Registers issues as a file owner: attached files stay visible to issue
  participants and are not collected by GC
- IssueDetail.attachments GraphQL field via @ResolveField, issue module untouched

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/modules/issue-attachment/presentation/controllers/issue-attachment.controller.ts

@@ -0,0 +1,87 @@
+import {
+  Body,
+  Controller,
+  Delete,
+  ForbiddenException,
+  Get,
+  HttpCode,
+  HttpStatus,
+  NotFoundException,
+  Param,
+  ParseIntPipe,
+  Post,
+} from '@nestjs/common';
+import { Session, type UserSession } from '@thallesp/nestjs-better-auth';
+import { ListIssueAttachmentsUseCase } from '../../application/use-cases/list-issue-attachments/list-issue-attachments.use-case.js';
+import { AttachFileUseCase } from '../../application/use-cases/attach-file/attach-file.use-case.js';
+import { DetachFileUseCase } from '../../application/use-cases/detach-file/detach-file.use-case.js';
+import { ListIssueAttachmentsQuery } from '../../application/use-cases/list-issue-attachments/list-issue-attachments.query.js';
+import { AttachFileCommand } from '../../application/use-cases/attach-file/attach-file.command.js';
+import { DetachFileCommand } from '../../application/use-cases/detach-file/detach-file.command.js';
+import { AttachFileRequestDto } from '../dto/attach-file.dto.js';
+import { IssueAttachmentNotFoundException } from '../../domain/exceptions/issue-attachment-not-found.exception.js';
+import { IssueNotFoundException } from '../../../issue/domain/exceptions/issue-not-found.exception.js';
+import { FileNotFoundException } from '../../../file/domain/exceptions/file-not-found.exception.js';
+import { FileForbiddenException } from '../../../file/domain/exceptions/file-forbidden.exception.js';
+
+/**
+ * Вложения задачи. Сам файл загружается отдельно (POST /files),
+ * здесь — только привязка к задаче. Скачивание — GET /files/:id/download.
+ */
+@Controller('issues/:issueId/attachments')
+export class IssueAttachmentController {
+  constructor(
+    private readonly listIssueAttachmentsUseCase: ListIssueAttachmentsUseCase,
+    private readonly attachFileUseCase: AttachFileUseCase,
+    private readonly detachFileUseCase: DetachFileUseCase,
+  ) {}
+
+  @Get()
+  list(@Param('issueId', ParseIntPipe) issueId: number, @Session() session: UserSession) {
+    return this.handleErrors(() =>
+      this.listIssueAttachmentsUseCase.execute(new ListIssueAttachmentsQuery(issueId, session.user.id)),
+    );
+  }
+
+  @Post()
+  attach(
+    @Param('issueId', ParseIntPipe) issueId: number,
+    @Body() dto: AttachFileRequestDto,
+    @Session() session: UserSession,
+  ) {
+    return this.handleErrors(() =>
+      this.attachFileUseCase.execute(new AttachFileCommand(issueId, dto.fileId, session.user.id)),
+    );
+  }
+
+  @Delete(':fileId')
+  @HttpCode(HttpStatus.NO_CONTENT)
+  async detach(
+    @Param('issueId', ParseIntPipe) issueId: number,
+    @Param('fileId') fileId: string,
+    @Session() session: UserSession,
+  ) {
+    await this.handleErrors(() =>
+      this.detachFileUseCase.execute(new DetachFileCommand(issueId, fileId, session.user.id)),
+    );
+  }
+
+  /** Транслирует доменные исключения в HTTP-ответ — это забота presentation-слоя */
+  private async handleErrors<T>(fn: () => Promise<T>): Promise<T> {
+    try {
+      return await fn();
+    } catch (error) {
+      if (
+        error instanceof IssueNotFoundException ||
+        error instanceof FileNotFoundException ||
+        error instanceof IssueAttachmentNotFoundException
+      ) {
+        throw new NotFoundException(error.message);
+      }
+      if (error instanceof FileForbiddenException) {
+        throw new ForbiddenException(error.message);
+      }
+      throw error;
+    }
+  }
+}