refactor(api): buses only in services, atomic commands, @Prop schemas

- Mongo read models are @Schema/@Prop classes (SchemaFactory), still
  loose: the props declared are the indexed or shaped ones.
- CommandBus and QueryBus are used by the application services alone.
  Duplicating a ticket, bulk updates, CSV imports, proposals and
  emptying the trash chain several commands, so they are service
  methods now and their composite commands are gone; every command
  handler is atomic. No forwardRef is needed.
- The due-date and trash timers are entry points: they live in the
  presenters and call the services. The automations event handler has
  its own file and calls AutomationsService.
- The tracker's user directory asks IdentityService; the composition
  root hands the identity application module to the tracker
  infrastructure (withIdentity), with no global module.

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

libs/api/tracker/application/src/lib/queries/get-showcase.query.ts

@@ -6,7 +6,7 @@ import { FindProjectsRepository } from '../ports/find-projects.repository';
 import { FindReleasesRepository } from '../ports/find-releases.repository';
 import { FindSprintsRepository } from '../ports/find-sprints.repository';
 
-import { PROPOSAL_LABEL } from '../commands/submit-proposal.command-handler';
+import { PROPOSAL_LABEL } from '../proposals';
 
 /** Tickets with this label are offered to newcomers on public pages. */
 export const GOOD_FIRST_LABEL = 'good-first-issue';