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/common/file.go

@@ -0,0 +1,77 @@
+// Copyright 2022 The Gitea Authors. All rights reserved.
+// Copyright 2020 The nektos/act Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package common
+
+import (
+	"fmt"
+	"io"
+	"os"
+)
+
+// CopyFile copy file
+func CopyFile(source, dest string) (err error) {
+	sourcefile, err := os.Open(source)
+	if err != nil {
+		return err
+	}
+
+	defer sourcefile.Close()
+
+	destfile, err := os.Create(dest)
+	if err != nil {
+		return err
+	}
+
+	defer destfile.Close()
+
+	_, err = io.Copy(destfile, sourcefile)
+	if err == nil {
+		sourceinfo, err := os.Stat(source)
+		if err != nil {
+			_ = os.Chmod(dest, sourceinfo.Mode())
+		}
+	}
+
+	return err
+}
+
+// CopyDir recursive copy of directory
+func CopyDir(source, dest string) (err error) {
+	// get properties of source dir
+	sourceinfo, err := os.Stat(source)
+	if err != nil {
+		return err
+	}
+
+	// create dest dir
+
+	err = os.MkdirAll(dest, sourceinfo.Mode())
+	if err != nil {
+		return err
+	}
+
+	objects, err := os.ReadDir(source)
+
+	for _, obj := range objects {
+		sourcefilepointer := source + "/" + obj.Name()
+
+		destinationfilepointer := dest + "/" + obj.Name()
+
+		if obj.IsDir() {
+			// create sub-directories - recursively
+			err = CopyDir(sourcefilepointer, destinationfilepointer)
+			if err != nil {
+				fmt.Println(err) //nolint:forbidigo // pre-existing issue from nektos/act
+			}
+		} else {
+			// perform copy
+			err = CopyFile(sourcefilepointer, destinationfilepointer)
+			if err != nil {
+				fmt.Println(err) //nolint:forbidigo // pre-existing issue from nektos/act
+			}
+		}
+	}
+	return err
+}