proxmox: review fixes, real-host validation record, changelog

Phase 10. Two review passes (go-operator-reviewer, /code-review high)
over the branch, recorded in docs/reviews/2026-09-23-proxmox-provider-review/:
9 findings fixed, 3 accepted as documented limits, 7 rejected with a
reason.

- Delete removes the seed between the stop and the destroy, so a failed
  seed delete leaves the VM for the next Delete instead of leaking the
  ISO; a Permanent refusal on the every-node path fails the call.
- Create skips a probe VMID whose listed name is someone else's without
  waiting on its lock.
- The three answers Phase 0 never captured are fixtures now: a missing
  storage is a 400 (the Checker reports StorageNotFound), a hibernated
  VM is destroyable (Delete destroys ours), a paused VM stops.
- TestProxmox_lifecycle and TestProxmoxCheck_realHost passed on pv1-1
  (PVE 9.2.20); the docs record the run and drop "not yet run".

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

docs/architecture.md

@@ -226,8 +226,9 @@ prov.Get    ──► /cluster/resources (absent = NotFound; lock or node unknow
                   + agent network-get-interfaces (first routable IPv4; agent not
                     up yet = Provisioning)
 prov.Delete ──► resources + config: gone, not ours or unmarked = leave it;
-                  hibernated = Permanent; stop → destroy (purge) → delete the seed
-                  on the VM's node (or on every node when no VM of ours was left)
+                  stop (unless stopped or hibernated) → delete the seed on the
+                  VM's node → destroy (purge); with no VM of ours left, the seed
+                  is deleted on every node
 prov.ListByTag ─► one /cluster/resources for the whole cluster, one config read per
                     candidate (tag or proxy- name); the description's mark decides
 Check       ──► per node: /version, node status, isoStorage status, templates in