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/infrastructure/src/lib/mongo/calendar-feeds.repository.ts

@@ -0,0 +1,46 @@
+import { Injectable } from '@nestjs/common';
+import { InjectModel } from '@nestjs/mongoose';
+import {
+  CalendarFeed,
+  CalendarFeedsRepository,
+} from '@task-stream/api/tracker/application';
+import { Model } from 'mongoose';
+import { CalendarFeedDoc, ReadModels } from './read-model.schemas';
+
+@Injectable()
+export class MongoCalendarFeedsRepository extends CalendarFeedsRepository {
+  constructor(
+    @InjectModel(ReadModels.CalendarFeed)
+    private readonly feeds: Model<CalendarFeedDoc>,
+  ) {
+    super();
+  }
+
+  async findByUser(userId: string): Promise<CalendarFeed | null> {
+    const doc = await this.feeds
+      .findOne({ id: userId })
+      .lean<CalendarFeedDoc>();
+    return doc ? toFeed(doc) : null;
+  }
+
+  async findByToken(token: string): Promise<CalendarFeed | null> {
+    const doc = await this.feeds.findOne({ token }).lean<CalendarFeedDoc>();
+    return doc ? toFeed(doc) : null;
+  }
+
+  async save(feed: CalendarFeed): Promise<void> {
+    await this.feeds.updateOne(
+      { id: feed.userId },
+      { $set: { token: feed.token, createdAt: feed.createdAt } },
+      { upsert: true },
+    );
+  }
+
+  async remove(userId: string): Promise<void> {
+    await this.feeds.deleteOne({ id: userId });
+  }
+}
+
+function toFeed(doc: CalendarFeedDoc): CalendarFeed {
+  return { userId: doc.id, token: doc.token, createdAt: doc.createdAt };
+}

libs/api/tracker/infrastructure/src/lib/mongo/find.repositories.ts

@@ -266,6 +266,25 @@ export class MongoFindIssuesRepository extends FindIssuesRepository {
     return docs.map(issueFromDoc);
   }
 
+  async findDatedFor(
+    userId: string,
+    projectIds: string[],
+  ): Promise<IssueReadModel[]> {
+    if (projectIds.length === 0) return [];
+    const docs = await this.issues
+      .find({
+        projectId: { $in: projectIds },
+        dueDate: { $ne: null },
+        trashedAt: null,
+        statusCategory: { $nin: FINISHED },
+        $or: [{ 'assignee.id': userId }, { 'watchers.id': userId }],
+      })
+      .sort({ dueDate: 1 })
+      .limit(1000)
+      .lean<IssueDoc[]>();
+    return docs.map(issueFromDoc);
+  }
+
   async findByProject(projectId: string): Promise<IssueReadModel[]> {
     const docs = await this.issues
       .find({ projectId, trashedAt: null })

libs/api/tracker/infrastructure/src/lib/mongo/read-model.schemas.ts

@@ -64,6 +64,12 @@ export interface GitIntegrationDoc {
   secret?: string;
   createdAt?: string;
 }
+export interface CalendarFeedDoc {
+  /** The user's id. */
+  id: string;
+  token: string;
+  createdAt: string;
+}
 export interface NotificationSettingsDoc {
   /** The user's id. */
   id: string;
@@ -85,6 +91,7 @@ export const ReadModels = {
   OutgoingWebhook: 'OutgoingWebhook',
   Automation: 'Automation',
   AutomationRun: 'AutomationRun',
+  CalendarFeed: 'CalendarFeed',
 } as const;
 
 /*
@@ -329,6 +336,17 @@ class AutomationRunDocument {
 export const AutomationRunSchema = SchemaFactory.createForClass(
   AutomationRunDocument,
 );
+/** One per person: the secret of their calendar URL. */
+@Schema({ ...LOOSE, collection: 'calendar_feeds' })
+class CalendarFeedDocument {
+  /** The user's id. */
+  @Prop({ type: String, required: true, unique: true }) id!: string;
+  @Prop({ type: String, required: true, unique: true }) token!: string;
+  @Prop({ type: String }) createdAt!: string;
+}
+export const CalendarFeedSchema =
+  SchemaFactory.createForClass(CalendarFeedDocument);
+
 // Redeliveries happen within minutes; a month of memory is plenty.
 AutomationRunSchema.index({ at: 1 }, { expireAfterSeconds: 30 * 86_400 });
 
@@ -347,6 +365,7 @@ export const READ_MODEL_SCHEMAS = [
   { name: ReadModels.Notification, schema: NotificationSchema },
   { name: ReadModels.NotificationSettings, schema: NotificationSettingsSchema },
   { name: ReadModels.SavedFilter, schema: SavedFilterSchema },
+  { name: ReadModels.CalendarFeed, schema: CalendarFeedSchema },
 ];
 
 /** A document as the model it holds: Mongo's own `_id` left out. */

libs/api/tracker/infrastructure/src/lib/tracker-infrastructure.module.ts

@@ -7,6 +7,7 @@ import {
   ChangeFeed,
   NotificationMailer,
   NotificationsRepository,
+  CalendarFeedsRepository,
   SavedFiltersRepository,
   GitIntegrationsRepository,
   OutgoingWebhooksRepository,
@@ -65,6 +66,7 @@ import { PostgresTrackerStreamsRepository } from './postgres/tracker-streams.rep
 import { RedisChangeFeed } from './realtime/redis-change-feed';
 import { RedisRateLimitStore } from './redis/redis-rate-limit.store';
 import { MongoNotificationsRepository } from './mongo/notifications.repository';
+import { MongoCalendarFeedsRepository } from './mongo/calendar-feeds.repository';
 import { MongoSavedFiltersRepository } from './mongo/saved-filters.repository';
 import { MongoGitIntegrationsRepository } from './mongo/git-integrations.repository';
 import { MongoOutgoingWebhooksRepository } from './mongo/outgoing-webhooks.repository';
@@ -130,6 +132,7 @@ const PORTS = [
   { provide: AttachmentStorage, useClass: FileSystemAttachmentStorage },
   // Notifications → MongoDB (per person), copies by e-mail → SMTP (optional)
   { provide: NotificationsRepository, useClass: MongoNotificationsRepository },
+  { provide: CalendarFeedsRepository, useClass: MongoCalendarFeedsRepository },
   { provide: SavedFiltersRepository, useClass: MongoSavedFiltersRepository },
   {
     provide: GitIntegrationsRepository,