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>

internal/provider/proxmox/get_test.go

@@ -341,8 +341,10 @@ func TestGet_unknownStatusIsTransient(t *testing.T) {
 	fx := newFixture(t, 1)
 	fx.addOurVM(testVMID, testName, "running").status = "unknown"
 	msg := assertGetFails(t, fx, provider.ErrTransient)
-	if !strings.Contains(msg, "pv1-1") {
-		t.Errorf("error = %s, want it to name the node", msg)
+	// On pv1-1 the first Get after Create met this with the node up: the
+	// listing had not reported the new VM yet (Phase 10 run, finding P6).
+	if !strings.Contains(msg, "pv1-1") || !strings.Contains(msg, "too new to be reported yet") {
+		t.Errorf("error = %s, want it to name the node and both causes", msg)
 	}
 	if n := fx.fake.callCount("VMConfig"); n != 0 {
 		t.Errorf("VMConfig calls = %d, want 0 while the node is unknown", n)