migrate site id to varchar instead of int

backend/apps/farms/tests.py

@@ -12,14 +12,19 @@ from apps.sync.models import ActiveSite
 
 def _gm_visible_site(*, owner: User, site_name: str, code: str) -> Site:
     """GM scope only sees sites linked to an ActiveSite they manage."""
+    site_id = f"{code}-0001"
     active_site = ActiveSite.objects.create(
         code=code,
         name=site_name,
+        source_site_id=site_id,
         api_base_url=f"https://{code}.example/api/v1",
         managed_by=owner,
     )
     return Site.objects.create(
-        site_name=site_name, user=owner, active_site=active_site
+        site_id=site_id,
+        site_name=site_name,
+        user=owner,
+        active_site=active_site,
     )