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>

env.example

@@ -57,6 +57,8 @@ UPDATE_GIT=true
 DEFAULT_FLAVOR_ID=
 FLAVOR_PREFERENCE=4090-24,4090-48,a5000,a100-40
 FLAVOR_FALLBACK=true
+# cheap = 1×GPU min vCPU/RAM; balanced ≈ 8/32GB; ram = max RAM among 1×GPU
+FLAVOR_SIZE_PRESET=cheap
 # Pools to probe before pick (ru-6 = Selectel multi-zone). Comma-separated.
 SCAN_POOLS=ru-6,ru-7
 DEFAULT_SPOT=true