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/identity/presenters/README.md

@@ -7,7 +7,8 @@ Adaptadores de entrada de identidad.
 
 ## Contenido
 
-- `auth/`: `AuthGuard` global, `@Public()`, `@CurrentUser()`, `@AccessToken()`, `@RequireAppRoles()`, `WsAuthenticator`
+- `auth/`: `AuthGuard` global, `@Public()`, `@OptionalAuth()` / `@ApiOptionalPireonAuth()` (lecturas de proyectos
+  públicos: sin token, el usuario es `undefined`), `@CurrentUser()`, `@AccessToken()`, `@RequireAppRoles()`, `WsAuthenticator`
   (subscriptions) y `@ApiPireonAuth()` (esquemas OAuth2 / Bearer de Pireon en OpenAPI).
 - `http/`: `AuthController` (`GET /api/auth/config`, `POST /api/auth/token`), `UsersController` (`/api/users/me`,
   directorio de Pireon) y `PireonWebhookController` (firma HMAC). Documentados con `@nestjs/swagger`.