fix: the membership status vocabulary moves beside Membership, so the Patreon client never imports the roster

240f11c made PatreonClient._membership import has_paid_access from membership_roster. test_gated_reason::test_no_fetch_path_can_read_the_roster failed on it, correctly: native_ingest_common is a fetch root, patreon_client is reachable from it, and no fetch path may be able to reach the roster. The roster is allowed to explain a skip, never to cause one.

MEMBERSHIP_STATUS and has_paid_access are pure platform knowledge with no database behind them. They move to native_ingest_common, next to the Membership type they interpret (the same move C7 made for Membership itself). membership_roster, membership_reconcile, patreon_client and the tests import them from there. There is no re-export from membership_roster.

The guard is unchanged. The lapsed-orphan skip from 240f11c stays as it was.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SHQB1YukL3VyvMK8rcbmV9

backend/app/services/patreon_client.py

@@ -58,6 +58,7 @@ from .native_ingest_common import (
     NativeDriftError,
     NativeIngestError,
     basename_from_url,
+    has_paid_access,
     make_session,
     retry_after_seconds,
 )
@@ -650,8 +651,6 @@ class PatreonClient:
         membership without a creator is something FC cannot vouch for, and
         dropping it would read downstream as a cancellation.
         """
-        from .membership_roster import has_paid_access
-
         attrs = member.get("attributes") or {}
         if "patron_status" not in attrs:
             raise PatreonDriftError(