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/web/tracker/infrastructure/src/lib/graphql/fragments.graphql

@@ -60,6 +60,12 @@ fragment ProjectFields on Project {
       archived
     }
     checklistBeforeDone
+    teams {
+      id
+      name
+      memberIds
+      archived
+    }
   }
 }
 
@@ -69,6 +75,7 @@ fragment IssueSummaryFields on Issue {
   key
   type
   area
+  team
   title
   status
   statusCategory