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/parse_env_file.go

@@ -0,0 +1,83 @@
+// Copyright 2022 The Gitea Authors. All rights reserved.
+// Copyright 2022 The nektos/act Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package container
+
+import (
+	"archive/tar"
+	"bufio"
+	"context"
+	"fmt"
+	"io"
+	"strings"
+
+	"gitea.com/gitea/runner/internal/act/common"
+
+	"golang.org/x/text/encoding/unicode"
+	"golang.org/x/text/transform"
+)
+
+func parseEnvFile(e Container, srcPath string, env *map[string]string) common.Executor {
+	localEnv := *env
+	return func(ctx context.Context) error {
+		envTar, err := e.GetContainerArchive(ctx, srcPath)
+		if err != nil {
+			return nil
+		}
+		defer envTar.Close()
+		reader := tar.NewReader(envTar)
+		_, err = reader.Next()
+		if err != nil && err != io.EOF {
+			return err
+		}
+		// Decode by BOM: Windows PowerShell 5.1 redirection writes UTF-16, and some
+		// tools emit a UTF-8 BOM. Without a BOM the file is read as UTF-8, as before.
+		decoded := transform.NewReader(reader, unicode.BOMOverride(unicode.UTF8.NewDecoder()))
+
+		s := bufio.NewScanner(decoded)
+		// Default 64 KiB max token size is too small for realistic env-file lines; allow up to 16 MiB.
+		s.Buffer(make([]byte, 0, 64*1024), 16*1024*1024)
+		for s.Scan() {
+			line := s.Text()
+			// GitHub's runner ignores blank lines
+			if strings.TrimSpace(line) == "" {
+				continue
+			}
+			singleLineEnv := strings.Index(line, "=")
+			multiLineEnv := strings.Index(line, "<<")
+			if singleLineEnv != -1 && (multiLineEnv == -1 || singleLineEnv < multiLineEnv) {
+				localEnv[line[:singleLineEnv]] = line[singleLineEnv+1:]
+			} else if multiLineEnv != -1 {
+				multiLineEnvContent := ""
+				multiLineEnvDelimiter := line[multiLineEnv+2:]
+				delimiterFound := false
+				for s.Scan() {
+					content := s.Text()
+					if content == multiLineEnvDelimiter {
+						delimiterFound = true
+						break
+					}
+					if multiLineEnvContent != "" {
+						multiLineEnvContent += "\n"
+					}
+					multiLineEnvContent += content
+				}
+				if err := s.Err(); err != nil {
+					return fmt.Errorf("reading env file: %w", err)
+				}
+				if !delimiterFound {
+					return fmt.Errorf("invalid format delimiter '%v' not found before end of file", multiLineEnvDelimiter)
+				}
+				localEnv[line[:multiLineEnv]] = multiLineEnvContent
+			} else {
+				return fmt.Errorf("invalid format '%v', expected a line with '=' or '<<'", line)
+			}
+		}
+		if err := s.Err(); err != nil {
+			return fmt.Errorf("reading env file: %w", err)
+		}
+		env = &localEnv
+		return nil
+	}
+}