feat: teams within a project

Projects keep teams of members in their settings (settings.teams; people
outside the project are dropped, teams are archived, not removed; absent
when saving means unchanged). Tickets go to a team (`team`, also filtered
in the list and in MCP search_issues), and a comment mentioning
@[Frontend](team-FRONT) tells each of its members. Settings has the teams
with their members, the ticket a «Equipo» select, the list a team filter,
and «@» offers the teams after the people.

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

libs/api/tracker/domain/src/lib/read-models/issue.read-model.ts

@@ -62,6 +62,8 @@ export class IssueReadModel {
   /** Ids from the project's settings. */
   type!: string;
   area!: string | null;
+  /** A team id of the project's settings. */
+  team!: string | null;
   title!: string;
   description!: string | null;
   status!: string;