fix(projects): stop the cockpit offering email controls the API rejects (stable) (#977)

Closes #969 on stable. Backport of #976.

The cockpit's email feed rendered preview/resend/cancel/retry/send-now for every mail regardless of role or permission, producing 404s (CRM document mail has no event_id; project ownership does not imply event ownership) and 403s (preview needs events.view, the write actions need email.send).

getProjectOverview now stamps each email with an authoritative canAct, mirroring filterOwnedEventIds; created_by is selected only for that check and stripped before the response. A missing canAct reads as false.

backend/src/routes/adminProjects.js

@@ -183,7 +183,7 @@ router.get('/:id/overview', requirePermission('events.view'), requireProjectOwne
     quotes: await userHasAnyPermission(req.admin.id, ['quotes.view']),
     contracts: await userHasAnyPermission(req.admin.id, ['contracts.view']),
   };
-  const overview = await projectService.getProjectOverview(parseInt(req.params.id, 10), perms);
+  const overview = await projectService.getProjectOverview(parseInt(req.params.id, 10), perms, req.admin);
   return successResponse(res, overview);
 }));