Document live vCenter ATVM datastore selection

- map AutomatedTest-VMBootImg-Gold to gold and Gold-2 to gold-2
- require live vCenter placement checks for explicit VM lists
- stop mixed gold/gold-2 requests before planning ATVM runs
- return hostname-only datastore inventories by default
- tell the operator about the vCenter placement check before showing run commands
- clarify that repo inventory files are not the source of truth for current datastore membership

atvm/inventory/overview.md

@@ -11,6 +11,8 @@ This directory contains the durable environment reference for the ATVM workspace
   - reserved IP ranges and per-IP role assignments
 - `specialized-reference.md`
   - map of the preserved detailed sections for zoning, ISO inventory, guest image inventory, guest configuration, gold images, and temporary clients
+- `vm-inventory.md`
+  - broad VM reference snapshot; do not use it for current `AutomatedTest-VMBootImg-Gold` / `AutomatedTest-VMBootImg-Gold-2` membership during ATVM run planning
 
 ## Preserved Source
 - Full original notes are preserved at: