docs(atvm): require explicit approval before any atvm_prep execution

atvm/docs/automation/atvm-prep-reference.md

@@ -56,6 +56,9 @@ For requests in this workspace, operator shorthand may be expanded as follows:
 - If only one side of the pair is supplied (`-c` or `-e`), auto-fill the other side from this mapping.
 - If both are supplied but conflict, stop and confirm before execution.
 
+4. Approval rule
+- Always show the exact planned `atvm_prep.py` command and wait for explicit operator approval before execution.
+
 ## Operational Flow
 High-level behavior across modes: