Merge gitea/act into act/

Merges the `gitea.com/gitea/act` fork into this repository as the `act/`
directory and consumes it as a local package. The `replace github.com/nektos/act
=> gitea.com/gitea/act` directive is removed; act's dependencies are merged
into the root `go.mod`.

- Imports rewritten: `github.com/nektos/act/pkg/...` → `gitea.com/gitea/act_runner/act/...`
  (flattened — `pkg/` boundary dropped to match the layout forgejo-runner adopted).
- Dropped act's CLI (`cmd/`, `main.go`) and all upstream project files; kept
  the library tree + `LICENSE`.
- Added `// Copyright <year> The Gitea Authors ...` / `// Copyright <year> nektos`
  headers to 104 `.go` files.
- Pre-existing act lint violations annotated inline with
  `//nolint:<linter> // pre-existing issue from nektos/act`.
  `.golangci.yml` is unchanged vs `main`.
- Makefile test target: `-race -short` (matches forgejo-runner).
- Pre-existing integration test failures fixed: race in parallel executor
  (atomic counters); TestSetupEnv / command_test / expression_test /
  run_context_test updated to match gitea fork runtime; TestJobExecutor and
  TestActionCache gated on `testing.Short()`.

Full `gitea/act` commit history is reachable via the second parent.

Co-Authored-By: Claude (Opus 4.7) <noreply@anthropic.com>

act/container/linux_container_environment_extensions_test.go

@@ -0,0 +1,70 @@
+// Copyright 2022 The Gitea Authors. All rights reserved.
+// Copyright 2022 The nektos/act Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package container
+
+import (
+	"fmt"
+	"os"
+	"runtime"
+	"strings"
+	"testing"
+
+	log "github.com/sirupsen/logrus"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestContainerPath(t *testing.T) {
+	type containerPathJob struct {
+		destinationPath string
+		sourcePath      string
+		workDir         string
+	}
+
+	linuxcontainerext := &LinuxContainerEnvironmentExtensions{}
+
+	if runtime.GOOS == "windows" {
+		cwd, err := os.Getwd()
+		if err != nil {
+			log.Error(err)
+		}
+
+		rootDrive := os.Getenv("SystemDrive")
+		rootDriveLetter := strings.ReplaceAll(strings.ToLower(rootDrive), `:`, "")
+		for _, v := range []containerPathJob{
+			{"/mnt/c/Users/act/go/src/github.com/nektos/act", "C:\\Users\\act\\go\\src\\github.com\\nektos\\act\\", ""},
+			{"/mnt/f/work/dir", `F:\work\dir`, ""},
+			{"/mnt/c/windows/to/unix", "windows\\to\\unix", rootDrive + "\\"},
+			{fmt.Sprintf("/mnt/%v/act", rootDriveLetter), "act", rootDrive + "\\"},
+		} {
+			if v.workDir != "" {
+				t.Chdir(v.workDir)
+			}
+
+			assert.Equal(t, v.destinationPath, linuxcontainerext.ToContainerPath(v.sourcePath))
+		}
+
+		t.Chdir(cwd)
+	} else {
+		cwd, err := os.Getwd()
+		if err != nil {
+			log.Error(err)
+		}
+		for _, v := range []containerPathJob{
+			{"/home/act/go/src/github.com/nektos/act", "/home/act/go/src/github.com/nektos/act", ""},
+			{"/home/act", `/home/act/`, ""},
+			{cwd, ".", ""},
+		} {
+			assert.Equal(t, v.destinationPath, linuxcontainerext.ToContainerPath(v.sourcePath))
+		}
+	}
+}
+
+type typeAssertMockContainer struct {
+	Container
+	LinuxContainerEnvironmentExtensions
+}
+
+// Type assert Container + LinuxContainerEnvironmentExtensions implements ExecutionsEnvironment
+var _ ExecutionsEnvironment = &typeAssertMockContainer{}