feat: a calendar to subscribe to, and the backlog's corners

- Each person can subscribe their dates in Google Calendar, Outlook or
  Apple Calendar: GET /api/calendar/{token}.ics (no session) brings
  their unfinished tickets with a due date (assigned or followed), the
  planned and running sprints and the planned releases of their
  projects, as all-day events linking to the web. The token is made,
  renewed or dropped under /me/calendar (and in GraphQL); in the web,
  from «Calendario» in «Mi trabajo».
- The backlog panel keeps the selected rows' background inside its
  rounded corners.

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

libs/api/tracker/presenters/src/lib/http/calendar.controller.ts

@@ -0,0 +1,96 @@
+import {
+  Controller,
+  Delete,
+  Get,
+  Header,
+  HttpCode,
+  NotFoundException,
+  Param,
+  Post,
+  Res,
+} from '@nestjs/common';
+import { ConfigService } from '@nestjs/config';
+import {
+  ApiNoContentResponse,
+  ApiOkResponse,
+  ApiOperation,
+  ApiProduces,
+  ApiTags,
+} from '@nestjs/swagger';
+import { User } from '@task-stream/api/identity/domain';
+import {
+  ApiPireonAuth,
+  CurrentUser,
+  Public,
+} from '@task-stream/api/identity/presenters';
+import { CalendarService } from '@task-stream/api/tracker/application';
+import type { Response } from 'express';
+import { CalendarFeedDto } from './dto/responses.dto';
+
+/**
+ * A person's calendar as iCalendar, for Google Calendar, Outlook or Apple
+ * Calendar to subscribe to. The URL carries a secret token instead of a
+ * session (calendar apps cannot sign in); the person makes, renews or
+ * drops it under /me/calendar.
+ */
+@ApiTags('Users')
+@Controller()
+export class CalendarController {
+  constructor(
+    private readonly calendar: CalendarService,
+    private readonly config: ConfigService,
+  ) {}
+
+  @Get('calendar/:file')
+  @Public()
+  @Header('Content-Type', 'text/calendar; charset=utf-8')
+  @Header('Cache-Control', 'private, max-age=300')
+  @ApiProduces('text/calendar')
+  @ApiOperation({
+    summary: 'A calendar to subscribe to (`{token}.ics`, no session)',
+    description:
+      'Unfinished tickets with a due date (assigned or followed), planned and running sprints, and planned releases with a date, as all-day events.',
+  })
+  async ics(@Param('file') file: string): Promise<string> {
+    const token = /^([\w-]{20,100})\.ics$/.exec(file)?.[1];
+    const body = token
+      ? await this.calendar.ics(token, this.config.get<string>('WEB_URL') ?? '')
+      : null;
+    if (body === null) throw new NotFoundException('Unknown calendar');
+    return body;
+  }
+
+  @Get('me/calendar')
+  @ApiPireonAuth()
+  @ApiOperation({ summary: 'My calendar URL, if I made one' })
+  @ApiOkResponse({ type: CalendarFeedDto })
+  @ApiNoContentResponse({ description: 'I have none' })
+  async mine(
+    @CurrentUser() me: User,
+    @Res({ passthrough: true }) response: Response,
+  ) {
+    const feed = await this.calendar.mine(me.id);
+    if (!feed) response.status(204);
+    return feed ?? undefined;
+  }
+
+  @Post('me/calendar')
+  @ApiPireonAuth()
+  @ApiOperation({
+    summary: 'A new secret calendar URL (the previous one stops working)',
+  })
+  @ApiOkResponse({ type: CalendarFeedDto })
+  @HttpCode(200)
+  create(@CurrentUser() me: User) {
+    return this.calendar.create(me.id);
+  }
+
+  @Delete('me/calendar')
+  @ApiPireonAuth()
+  @ApiOperation({ summary: 'My calendar URL stops working' })
+  @ApiNoContentResponse()
+  @HttpCode(204)
+  async revoke(@CurrentUser() me: User): Promise<void> {
+    await this.calendar.revoke(me.id);
+  }
+}

libs/api/tracker/presenters/src/lib/http/dto/responses.dto.ts

@@ -831,6 +831,15 @@ export class MyNotificationsDto {
   unread!: number;
 }
 
+export class CalendarFeedDto {
+  @ApiProperty({
+    description:
+      'Secret of the calendar URL: GET /api/calendar/{token}.ics (iCalendar, no session)',
+  })
+  token!: string;
+  @ApiProperty() createdAt!: string;
+}
+
 export class NotificationSettingsResponseDto {
   @ApiProperty({ description: 'Copies by e-mail' }) email!: boolean;
   @ApiProperty({ description: 'Whether this installation can send e-mail' })