fix(data): make postgres snapshot migrations idempotent

crates/aether-data/adapters/postgres/migrations/20260831000000_enforce_ldap_config_singleton.sql

@@ -30,5 +30,9 @@ BEGIN
         ADD CONSTRAINT ldap_configs_singleton_key_key UNIQUE (singleton_key);
 EXCEPTION
     WHEN duplicate_object THEN NULL;
+    -- The empty-database snapshot already materializes this constraint. PostgreSQL
+    -- reports the existing constraint's backing relation as duplicate_table (42P07)
+    -- rather than duplicate_object, so treat that known idempotent case the same way.
+    WHEN duplicate_table THEN NULL;
 END
 $migration$;

crates/aether-data/adapters/postgres/migrations/20260903000000_add_routing_group_sort_order.sql

@@ -1,5 +1,8 @@
 ALTER TABLE public.routing_groups
-    ADD COLUMN sort_order bigint NOT NULL DEFAULT 0;
+    -- The empty-database snapshot may already contain the current logical
+    -- schema. Keep the incremental migration safe for both snapshot and
+    -- legacy databases.
+    ADD COLUMN IF NOT EXISTS sort_order bigint NOT NULL DEFAULT 0;
 
 CREATE INDEX IF NOT EXISTS routing_groups_enabled_sort_idx
     ON public.routing_groups (enabled DESC, sort_order, name, id);