Add external calendar profile contract

docs/MODULE_ARCHITECTURE.md

@@ -208,7 +208,8 @@ Other stable runtime capabilities currently include:
 - `identity.directory` and `identity.search`
 - `organizations.directory`
 - `idm.directory`
-- `calendar.outbox` and `calendar.scheduling`
+- `calendar.outbox`, `calendar.scheduling`, `calendar.invitations`, and
+  `calendar.externalProfiles`
 - `poll.scheduling`
 - `notifications.dispatch`
 - `workflow.definitionContributions` and `workflow.runtimeWorker`
@@ -286,7 +287,8 @@ Current named interfaces, generated from the source manifests by the workspace
 contract checks, are:
 
 - `addresses.contact_writer`, `addresses.lookup`, `addresses.recipient_source`
-- `calendar.outbox`, `calendar.scheduling`
+- `calendar.external_profiles`, `calendar.invitations`, `calendar.outbox`,
+  `calendar.scheduling`
 - `campaigns.access`, `campaigns.delivery_tasks`,
   `campaigns.mail_policy_context`, `campaigns.policy_context`,
   `campaigns.retention`