Clean child sessions in iam membership migration

Signed-off-by: Émile Ré <emile@getprobo.com>

pkg/coredata/migrations/20260119T182800.sql

@@ -50,7 +50,8 @@ updated_profiles AS (
         old_to_new m
     WHERE
         mp.membership_id = m.old_id RETURNING id
-)
+),
+deleted_memberships AS (
     DELETE FROM
         iam_memberships
     WHERE
@@ -59,4 +60,14 @@ WHERE
                 old_id
             FROM
                 old_to_new
-    ) RETURNING id;
+        ) RETURNING id
+)
+DELETE FROM
+    iam_sessions
+WHERE
+    membership_id IN (
+        SELECT
+            old_id
+        FROM
+            old_to_new
+    );