feat: guest role for clients and outsiders

A project member can be a GUEST. In a private project a guest only sees
the tickets they take part in (opened, assigned or followed): every other
ticket answers 404, also in my work, realtime changes, blockers and
linked tickets, and project-wide views (activity, statistics, dashboard,
releases, sprints, epics, trash) answer 403. Guests open tickets without
assigning or planning them, and comment, attach, follow and vote on their
own; they change nothing else. In a public project they see what anyone
does. The web gives them only Tablero, Lista and Miembros and loads none
of the project-wide data.

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

libs/api/tracker/application/src/lib/commands/vote-issue.command-handler.ts

@@ -25,6 +25,7 @@ export class VoteIssueCommandHandler
         `You are not a member of project ${project.key}`,
       );
     project.assertNotArchived();
+    this.access.assertSees(project, issue, command.actorId);
     if (issue.trashedAt)
       throw new BusinessRuleError(`${issue.key} is in the trash`);
     issue.vote(command.actorId, command.on);