feat: handle Kubernetes List objects in local/stdin input (#43)

When piping `kubectl get` output (which wraps resources in a `kind: List`
object), `visitLocalObjects` would fail because the List itself has no
`managedFields`. Now checks `obj.IsList()` and iterates through items.

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: knight42

README.md

@@ -11,6 +11,18 @@ to show who last modified the field.
 As long as the field `.metadata.manageFields` of the resource is set properly, this command
 is able to display the manager of each field.
 
+`kubectl-blame` can work in two ways:
+
+1. **Directly from the cluster** — fetch and blame resources in one step:
+   ```
+   kubectl blame deployments my-app
+   ```
+2. **From piped input** — use `kubectl get` (or any command that outputs YAML/JSON) and pipe the result:
+   ```
+   kubectl get deployments -o yaml | kubectl blame
+   ```
+   This also works with Kubernetes List objects (e.g., `kind: List`), so you can pipe the output of `kubectl get` which wraps multiple resources in a List.
+
 [![asciicast](https://asciinema.org/a/375008.svg)](https://asciinema.org/a/375008)
 
 ## Installing

cmd/blame.go

@@ -122,9 +122,21 @@ func (o *Options) visitLocalObjects(visit func(object metav1.Object) error) erro
 			}
 			return err
 		}
-		err = visit(obj)
-		if err != nil {
-			return err
+		if obj.IsList() {
+			list, err := obj.ToList()
+			if err != nil {
+				return err
+			}
+			for i := range list.Items {
+				if err := visit(&list.Items[i]); err != nil {
+					return err
+				}
+			}
+		} else {
+			err = visit(obj)
+			if err != nil {
+				return err
+			}
 		}
 	}
 	return nil

cmd/blame_test.go

@@ -55,6 +55,9 @@ func TestBlameLocalFile(t *testing.T) {
 		"multi-manager-list-item": {
 			inputFile: "multi-manager-list-item.yaml",
 		},
+		"list": {
+			inputFile: "list.yaml",
+		},
 	}
 	for name, tc := range testCases {
 		t.Run(name, func(t *testing.T) {