#19676: Email & Calendar tabs error on custom objects with join-table relations to Person

Bug

Custom objects that reach Person through a join table render the Email and Calendar tabs in the record detail view, but clicking either shows "An error occurred". Built-in objects like Company work because they have a direct people relation to Person.

Reproduction

1. Settings → Data Model → create a custom object peopleList (Folk-style ad-hoc list of people)
2. Create a custom join object peopleListMembership with two MANY_TO_ONE relation fields:
   • peopleList → peopleList
   • person → person
3. Open any peopleList record
4. Click the Email or Calendar tab in the right-side panel

Expected

Either:

• the tab walks join-table relations transitively to find Person records and shows the union of their messages/events; or
• the tab is hidden when the relation path can't be resolved.

Actual

Tab renders a loading state, then displays "An error occurred". The global messageThreads and calendarEvents GraphQL queries work fine — this is purely a UI relation-traversal limitation when the path to Person is mediated by a join object.

Environment

• Twenty v1.21.x (self-hosted, Docker)
• Workspace has both built-in objects (person, company, opportunity) and the two custom objects above

Workaround

Tell users those tabs are dead on custom objects with join-table relations — use Notes / Tasks / Files / Members instead.

Suggested fix

Either generalise the relation walker so multi-hop paths through join tables also resolve, or auto-hide Email/Calendar tabs when no direct people relation exists on the object.