feat: pinned tickets, at hand on the home page and in search

Each person pins up to 20 tickets from the ticket's page («Fijar»). They
show as a strip under the projects on the home page and in the search
palette before typing. Private and without history, like the views of
«my work» (Mongo `pinned_issues`); tickets in the trash or out of reach
are left out, and when the list is full the unreadable ones are dropped
first.

API: GET /api/me/pins, PUT/DELETE /api/issues/{issue}/pin; GraphQL
myPins, pinIssue, unpinIssue and Issue.pinned.

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

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

@@ -13,6 +13,7 @@ import {
   ReleaseReadModel,
   SavedFilterReadModel,
   MyViewReadModel,
+  PinnedIssueReadModel,
   SprintReadModel,
   implicitRank,
 } from '@task-stream/api/tracker/domain';
@@ -42,6 +43,7 @@ export type TimelineDoc = Doc<IssueTimelineEntry>;
 export type NotificationDoc = Doc<NotificationReadModel>;
 export type SavedFilterDoc = Doc<SavedFilterReadModel>;
 export type MyViewDoc = Doc<MyViewReadModel>;
+export type PinnedIssueDoc = PinnedIssueReadModel & { _id?: Types.ObjectId };
 export type OutgoingWebhookDoc = Doc<OutgoingWebhook>;
 export type AutomationDoc = Doc<Automation>;
 export interface AutomationRunDoc {
@@ -104,6 +106,7 @@ export const ReadModels = {
   NotificationSettings: 'NotificationSettings',
   SavedFilter: 'SavedFilter',
   MyView: 'MyView',
+  PinnedIssue: 'PinnedIssue',
   Sprint: 'SprintReadModel',
   GitIntegration: 'GitIntegration',
   OutgoingWebhook: 'OutgoingWebhook',
@@ -322,6 +325,16 @@ class MyViewDocument {
 }
 export const MyViewSchema = SchemaFactory.createForClass(MyViewDocument);
 
+@Schema({ ...LOOSE, collection: 'pinned_issues' })
+class PinnedIssueDocument {
+  @Prop({ type: String }) ownerId!: string;
+  @Prop({ type: String }) issueId!: string;
+  @Prop({ type: String }) pinnedAt!: string;
+}
+export const PinnedIssueSchema =
+  SchemaFactory.createForClass(PinnedIssueDocument);
+PinnedIssueSchema.index({ ownerId: 1, issueId: 1 }, { unique: true });
+
 @Schema({ ...LOOSE, collection: 'git_integrations' })
 class GitIntegrationDocument {
   /** The project's id. */
@@ -424,6 +437,7 @@ export const READ_MODEL_SCHEMAS = [
   { name: ReadModels.NotificationSettings, schema: NotificationSettingsSchema },
   { name: ReadModels.SavedFilter, schema: SavedFilterSchema },
   { name: ReadModels.MyView, schema: MyViewSchema },
+  { name: ReadModels.PinnedIssue, schema: PinnedIssueSchema },
   { name: ReadModels.CalendarFeed, schema: CalendarFeedSchema },
   { name: ReadModels.DashboardShare, schema: DashboardShareSchema },
   { name: ReadModels.PushSubscription, schema: PushSubscriptionSchema },