feat(cli): add --no-build flag to state push for state-only updates (#21374)

## Summary

Adds a `--no-build` flag to `coder state push` that updates the
Terraform state directly without triggering a workspace build.

## Use Case

This enables state-only migrations, such as migrating Kubernetes
resources from deprecated types (e.g., `kubernetes_config_map`) to
versioned types (e.g., `kubernetes_config_map_v1`):

```bash
coder state pull my-workspace > state.json
terraform init
terraform state rm -state=state.json kubernetes_config_map.example
terraform import -state=state.json kubernetes_config_map_v1.example default/example
coder state push --no-build my-workspace state.json
```

## Changes

- Add `PUT /api/v2/workspacebuilds/{id}/state` endpoint to update state
without triggering a build
- Add `UpdateWorkspaceBuildState` SDK method
- Add `--no-build`/`-n` flag to `coder state push`
- Add confirmation prompt (can be skipped with `--yes`/`-y`) since this
is a potentially dangerous operation
- Add test for `--no-build` functionality

Fixes #21336

cli/state.go

@@ -87,6 +87,7 @@ func buildNumberOption(n *int64) serpent.Option {
 
 func (r *RootCmd) statePush() *serpent.Command {
 	var buildNumber int64
+	var noBuild bool
 	cmd := &serpent.Command{
 		Use:   "push <workspace> <file>",
 		Short: "Push a Terraform state file to a workspace.",
@@ -126,6 +127,16 @@ func (r *RootCmd) statePush() *serpent.Command {
 				return err
 			}
 
+			if noBuild {
+				// Update state directly without triggering a build.
+				err = client.UpdateWorkspaceBuildState(inv.Context(), build.ID, state)
+				if err != nil {
+					return err
+				}
+				_, _ = fmt.Fprintln(inv.Stdout, "State updated successfully.")
+				return nil
+			}
+
 			build, err = client.CreateWorkspaceBuild(inv.Context(), workspace.ID, codersdk.CreateWorkspaceBuildRequest{
 				TemplateVersionID: build.TemplateVersionID,
 				Transition:        build.Transition,
@@ -139,6 +150,12 @@ func (r *RootCmd) statePush() *serpent.Command {
 	}
 	cmd.Options = serpent.OptionSet{
 		buildNumberOption(&buildNumber),
+		{
+			Flag:          "no-build",
+			FlagShorthand: "n",
+			Description:   "Update the state without triggering a workspace build. Useful for state-only migrations.",
+			Value:         serpent.BoolOf(&noBuild),
+		},
 	}
 	return cmd
 }