feat(web): admin panel member management page (ATB-43) (#73)
* feat(web): add canManageRoles session helper (ATB-43)
* feat(appview): include uri in GET /api/admin/roles response (ATB-43)
Add rkey and did fields to the roles DB query, then construct the AT URI
(at://<did>/space.atbb.forum.role/<rkey>) in the response map so the
admin members page dropdown can submit a valid roleUri.
* style(web): add admin member table CSS classes (ATB-43)
* feat(web): add GET /admin/members page and POST proxy route (ATB-43)
* fix(web): add manageRoles permission gate to POST proxy route (ATB-43)
* docs: mark ATB-42 and ATB-43 complete in project plan
* docs: add ATB-43 implementation plan
* fix(web): address PR review feedback on admin members page (ATB-43)
* fix(web): use canManageRoles(auth) instead of hardcoded false in rolesJson error path