feat(campaigns): add portable campaign transfers

tests/test_route_registration.py

@@ -13,6 +13,7 @@ from govoplan_campaign.backend.routes.operations import router as operations_rou
 from govoplan_campaign.backend.routes.reports import router as reports_router
 from govoplan_campaign.backend.routes.schedules import router as schedules_router
 from govoplan_campaign.backend.routes.sharing import router as sharing_router
+from govoplan_campaign.backend.routes.transfers import router as transfers_router
 from govoplan_campaign.backend.routes.versions import router as versions_router
 
 
@@ -27,6 +28,7 @@ def _operation_keys(candidate_router) -> list[tuple[str, str]]:
 def test_campaign_router_composes_every_workflow_operation_once() -> None:
     workflow_routers = (
         operations_router,
+        transfers_router,
         campaigns_router,
         assignments_router,
         collaboration_router,
@@ -46,7 +48,7 @@ def test_campaign_router_composes_every_workflow_operation_once() -> None:
     actual = _operation_keys(router)
 
     assert actual == expected
-    assert len(actual) == 93
+    assert len(actual) == 96
     assert not [operation for operation, count in Counter(actual).items() if count > 1]
 
 
@@ -57,6 +59,10 @@ def test_key_routes_are_owned_by_their_focused_router() -> None:
             ("POST", "/campaigns/operations/artifacts/reconcile"),
         ),
         (campaigns_router, ("GET", "/campaigns/{campaign_id}/workspace")),
+        (
+            transfers_router,
+            ("POST", "/campaign-transfers/imports/preview"),
+        ),
         (collaboration_router, ("POST", "/campaigns/{campaign_id}/collaboration")),
         (assignments_router, ("POST", "/campaigns/{campaign_id}/assignments")),
         (versions_router, ("POST", "/campaigns/versions/{version_id}/build")),