feat(campaigns): add governed collaboration thread

tests/test_route_registration.py

@@ -5,6 +5,7 @@ from collections import Counter
 from govoplan_campaign.backend.router import router
 from govoplan_campaign.backend.routes.attachments import router as attachments_router
 from govoplan_campaign.backend.routes.campaigns import router as campaigns_router
+from govoplan_campaign.backend.routes.collaboration import router as collaboration_router
 from govoplan_campaign.backend.routes.delivery import router as delivery_router
 from govoplan_campaign.backend.routes.jobs import router as jobs_router
 from govoplan_campaign.backend.routes.operations import router as operations_router
@@ -26,6 +27,7 @@ def test_campaign_router_composes_every_workflow_operation_once() -> None:
     workflow_routers = (
         operations_router,
         campaigns_router,
+        collaboration_router,
         versions_router,
         jobs_router,
         reports_router,
@@ -42,7 +44,7 @@ def test_campaign_router_composes_every_workflow_operation_once() -> None:
     actual = _operation_keys(router)
 
     assert actual == expected
-    assert len(actual) == 81
+    assert len(actual) == 86
     assert not [operation for operation, count in Counter(actual).items() if count > 1]
 
 
@@ -53,6 +55,7 @@ def test_key_routes_are_owned_by_their_focused_router() -> None:
             ("POST", "/campaigns/operations/artifacts/reconcile"),
         ),
         (campaigns_router, ("GET", "/campaigns/{campaign_id}/workspace")),
+        (collaboration_router, ("POST", "/campaigns/{campaign_id}/collaboration")),
         (versions_router, ("POST", "/campaigns/versions/{version_id}/build")),
         (jobs_router, ("GET", "/campaigns/{campaign_id}/jobs")),
         (reports_router, ("GET", "/campaigns/{campaign_id}/report")),