proxmox: Get, ListByTag and task polling

Get follows spec entry 9's check order (lock and unknown status before
the name, suspended is Stopped after the name and mark checks), reads
status/current so paused is Stopped, and maps the three agent messages
of entry 7. ListByTag reads one config per candidate and fails whole
only on the resources call or an ended ctx. waitTask polls the UPID's
node every budgets.poll, logs failed tasks at V(1) and counts
"WARNINGS: <n>" as success; waitUnlocked serves Create's ownership check.

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

internal/provider/proxmox/proxmox_test.go

@@ -216,16 +216,14 @@ func TestWrapErr_carriesProviderNameOpAndID(t *testing.T) {
 }
 
 // TestStubs_answerTransient keeps a Proxy on this provider retrying, not
-// latched, until the methods are implemented in later phases.
+// latched, until Create and Delete are implemented in later phases.
 func TestStubs_answerTransient(t *testing.T) {
 	t.Parallel()
 	ctx := context.Background()
 	p := newProvider("proxmox-home", testConfig(), nil)
 	_, createErr := p.Create(ctx, provider.CreateRequest{Name: "proxy-x"})
-	_, getErr := p.Get(ctx, "vms/150042/proxy-x")
 	deleteErr := p.Delete(ctx, "vms/150042/proxy-x")
-	_, listErr := p.ListByTag(ctx)
-	for op, err := range map[string]error{"create": createErr, "get": getErr, "delete": deleteErr, "list": listErr} {
+	for op, err := range map[string]error{"create": createErr, "delete": deleteErr} {
 		if !errors.Is(err, provider.ErrTransient) {
 			t.Errorf("%s error = %v, want ErrTransient", op, err)
 		}