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/shared/application/src/index.ts

@@ -1,3 +1,4 @@
 export * from './lib/ports/event-store';
 export * from './lib/aggregate-rehydrator';
 export * from './lib/shared.module';
+export * from './lib/event-recorder';

libs/api/shared/application/src/lib/event-recorder.ts

@@ -0,0 +1,35 @@
+import { Injectable } from '@nestjs/common';
+import { ConcurrencyError, DomainEvent } from '@task-stream/api/shared/domain';
+import { EventStore } from './ports/event-store';
+
+/**
+ * Appends a domain event to a stream that no aggregate of ours owns (e.g. a
+ * user, owned by Pireon), at the next position. Like any stored event, it
+ * reaches the event handlers and sagas of every context through the events
+ * bridge.
+ */
+@Injectable()
+export class EventRecorder {
+  constructor(private readonly eventStore: EventStore) {}
+
+  async record(streamId: string, event: DomainEvent): Promise<void> {
+    for (let attempt = 1; ; attempt++) {
+      const position =
+        (await this.eventStore.getEventsByStreamId(streamId)).length + 1;
+      try {
+        await this.eventStore.persist({
+          streamId,
+          position,
+          type: event.constructor.name,
+          data: JSON.parse(
+            JSON.stringify({ ...event, aggregateVersion: position }),
+          ),
+        });
+        return;
+      } catch (error) {
+        // Someone appended meanwhile: take the next position.
+        if (!(error instanceof ConcurrencyError) || attempt === 3) throw error;
+      }
+    }
+  }
+}

libs/api/shared/application/src/lib/shared.module.ts

@@ -1,11 +1,12 @@
 import { DynamicModule, Global, Module, Type } from '@nestjs/common';
 import { CqrsModule } from '@nestjs/cqrs';
 import { AggregateRehydrator } from './aggregate-rehydrator';
+import { EventRecorder } from './event-recorder';
 
 /**
  * Shared building blocks for every bounded context: the event store (from
- * the infrastructure module plugged in by the composition root) and the
- * AggregateRehydrator.
+ * the infrastructure module plugged in by the composition root), the
+ * AggregateRehydrator and the EventRecorder.
  */
 @Global()
 @Module({})
@@ -16,8 +17,8 @@ export class SharedModule {
     return {
       module: SharedModule,
       imports: [CqrsModule, infrastructureModule],
-      providers: [AggregateRehydrator],
-      exports: [infrastructureModule, AggregateRehydrator],
+      providers: [AggregateRehydrator, EventRecorder],
+      exports: [infrastructureModule, AggregateRehydrator, EventRecorder],
     };
   }
 }