refactor: move act under internal

The runner is an application, not a library. `act/model` and
`act/exprparser` were the last packages anything outside this repository
consumed and they now live in actionslib, so nothing needs the rest of
`act` to be importable, and keeping it importable invites the coupling
that was just removed.

Import paths only, the files are unchanged.

Assisted-by: Codet:GPT-5.1-Codex

internal/act/container/docker_stub.go

@@ -0,0 +1,79 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// Copyright 2023 The nektos/act Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+//go:build WITHOUT_DOCKER || !(linux || darwin || windows || netbsd)
+
+package container
+
+import (
+	"context"
+	"errors"
+	"runtime"
+	"time"
+
+	"gitea.com/gitea/runner/internal/act/common"
+
+	"github.com/moby/moby/api/types/system"
+)
+
+// ImageExistsLocally returns a boolean indicating if an image with the
+// requested name, tag and architecture exists in the local docker image store
+func ImageExistsLocally(ctx context.Context, imageName, platform string) (bool, error) {
+	return false, errors.New("Unsupported Operation")
+}
+
+// RemoveImage removes image from local store, the function is used to run different
+// container image architectures
+func RemoveImage(ctx context.Context, imageName string, force, pruneChildren bool) (bool, error) {
+	return false, errors.New("Unsupported Operation")
+}
+
+// NewDockerBuildExecutor function to create a run executor for the container
+func NewDockerBuildExecutor(input NewDockerBuildExecutorInput) common.Executor {
+	return func(ctx context.Context) error {
+		return errors.New("Unsupported Operation")
+	}
+}
+
+// NewDockerPullExecutor function to create a run executor for the container
+func NewDockerPullExecutor(input NewDockerPullExecutorInput) common.Executor {
+	return func(ctx context.Context) error {
+		return errors.New("Unsupported Operation")
+	}
+}
+
+// NewContainer creates a reference to a container
+func NewContainer(input *NewContainerInput) ExecutionsEnvironment {
+	return nil
+}
+
+func RunnerArch(ctx context.Context) string {
+	return runtime.GOOS
+}
+
+func GetHostInfo(ctx context.Context) (info system.Info, err error) {
+	return system.Info{}, nil
+}
+
+func NewDockerVolumeRemoveExecutor(volume string, force bool) common.Executor {
+	return func(ctx context.Context) error {
+		return nil
+	}
+}
+
+func NewDockerNetworkCreateExecutor(name string, opts NewDockerNetworkCreateExecutorInput) common.Executor {
+	return func(ctx context.Context) error {
+		return nil
+	}
+}
+
+func NewDockerNetworkRemoveExecutor(name string) common.Executor {
+	return func(ctx context.Context) error {
+		return nil
+	}
+}
+
+func RemoveOrphanNetworks(ctx context.Context, runnerUUID string, createdBefore time.Time) error {
+	return nil
+}