feat: public projects, project deletion and sagas

Public projects:
- Project.isPublic (create/update, owners and admins). Anyone can read a
  public project without a token: project, board, tickets, comments,
  history, releases, activity, tracking and statistics, over GraphQL and
  REST. Writes stay for members (401 anonymous, 403 outsiders).
- @OptionalAuth() / @ApiOptionalPireonAuth(): anonymous callers allowed,
  invalid tokens still rejected. ReadAccess lets anonymous viewers read
  public projects only; linked tickets are filtered by visibility.
- publicProjects (GraphQL) and GET /api/explore/projects (REST).
- Web: «Explorar» page, project pages open without a session (read-only
  notice, sign-in hints), public badge, visibility switch in settings,
  no realtime subscriptions without a session.

Project deletion:
- Owner only, confirming the key (deleteProject / DELETE
  /api/projects/{project}?confirm=KEY). The key is freed; the read model
  drops the project and members are notified (web goes home).

Sagas (run by the EventsBridge after projections, durable and ordered):
- ProjectDeletionSaga: project deleted → delete its tickets and releases;
  ticket deleted → purge its comments and drop links from other tickets.
- ReleaseArchivedSaga: unfinished tickets leave an archived release.
- UserDeactivatedSaga: the Pireon webhook records UserDeactivatedEvent in
  the event store (EventRecorder); the tracker unassigns that user's open
  tickets as the system actor.
- Internal idempotent commands; domain refusals are logged and skipped,
  concurrency conflicts retried. Affected streams come from the event store
  (TrackerStreamsRepository).

Tests: domain lifecycle specs, saga specs run like the bridge, facade
tests, e2e for public access, cascade deletion, archived releases and
deactivation webhook. Docs, READMEs, schema.gql/openapi.json and Word/PDF
updated.

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

libs/api/tracker/domain/src/lib/issue/issue.ts

@@ -5,6 +5,7 @@ import {
 } from '@task-stream/api/shared/domain';
 import { IssueAssignedEvent } from '../events/issue-assigned.event';
 import { IssueCreatedEvent } from '../events/issue-created.event';
+import { IssueDeletedEvent } from '../events/issue-deleted.event';
 import { IssueLinkedEvent } from '../events/issue-linked.event';
 import { IssueReleaseChangedEvent } from '../events/issue-release-changed.event';
 import { IssueStatusChangedEvent } from '../events/issue-status-changed.event';
@@ -83,6 +84,7 @@ export class Issue extends VersionedAggregateRoot implements IssueProps {
   public links: IssueLink[] = [];
   public createdAt!: string;
   public updatedAt!: string;
+  public deleted = false;
 
   constructor(id: string) {
     super();
@@ -214,6 +216,25 @@ export class Issue extends VersionedAggregateRoot implements IssueProps {
     );
   }
 
+  /** Deletes the ticket (its project was deleted). Idempotent. */
+  delete(actorId: string): void {
+    if (this.deleted) return;
+    this.apply(
+      new IssueDeletedEvent(actorId, this.id, this.projectId, this.key),
+    );
+  }
+
+  /** Drops every link to `targetIssueId` (that ticket was deleted). */
+  unlinkAllTo(actorId: string, targetIssueId: string): void {
+    for (const link of this.links.filter(
+      (l) => l.targetIssueId === targetIssueId,
+    )) {
+      this.apply(
+        new IssueUnlinkedEvent(actorId, this.id, this.projectId, { ...link }),
+      );
+    }
+  }
+
   /* ---- State transitions (also replayed by loadFromHistory) ---- */
 
   onIssueCreatedEvent({ issue }: IssueCreatedEvent): void {
@@ -255,6 +276,10 @@ export class Issue extends VersionedAggregateRoot implements IssueProps {
     this.updatedAt = event.occurredAt;
   }
 
+  onIssueDeletedEvent(): void {
+    this.deleted = true;
+  }
+
   onIssueReleaseChangedEvent(event: IssueReleaseChangedEvent): void {
     this.releaseId = event.releaseId;
     this.updatedAt = event.occurredAt;