feat(scheduling): expose invitation delivery capability

src/govoplan_scheduling/backend/schemas.py

@@ -320,6 +320,7 @@ class SchedulingRequestResponse(BaseModel):
     anonymous_password_protection_enabled: bool
     public_participation_policy_enforcement_available: bool | None = None
     public_participation_policy_enforcement_reason: str | None = None
+    participant_invitation_delivery_available: bool | None = None
     effective_participant_visibility: SchedulingParticipantVisibility
     participant_aggregate: SchedulingParticipantAggregateResponse
     participant_visibility_decision: SchedulingParticipantVisibilityDecisionResponse

src/govoplan_scheduling/backend/service.py

@@ -3859,6 +3859,11 @@ def scheduling_request_response(
             "details": {},
         }
     public_policy_available = _poll_participation_provider() is not None
+    participant_invitation_delivery_available = (
+        notification_dispatch_provider(get_registry()) is not None
+        if full_roster
+        else None
+    )
     return {
         "id": request.id,
         "tenant_id": request.tenant_id if full_roster else None,
@@ -3890,6 +3895,9 @@ def scheduling_request_response(
             if public_policy_available or not full_roster
             else PUBLIC_PARTICIPATION_POLICY_UNAVAILABLE_REASON
         ),
+        "participant_invitation_delivery_available": (
+            participant_invitation_delivery_available
+        ),
         "effective_participant_visibility": visibility_decision["effective_visibility"],
         "participant_aggregate": _participant_aggregate(active_participants),
         "participant_visibility_decision": visibility_decision,