Pick cheapest GPU SKU and pin the VM to an existing disk AZ.

Scan ru-6 by Nova availability zones (a/b/c). First boot uses FLAVOR_SIZE_PRESET=cheap; reruns stay on the disk segment.

Co-authored-by: Cursor <cursoragent@cursor.com>

scripts/migrate_local_configs.py

@@ -67,6 +67,7 @@ _VARS_PREFERRED = {
     "DEFAULT_SPOT",
     "SCAN_POOLS",
     "FLAVOR_PREFERENCE",
+    "FLAVOR_SIZE_PRESET",
     "SWARMUI_LOCAL_PORT",
 }