refactor: drop logrus and other direct dependencies (#1319)

After https://gitea.com/gitea/runner/pulls/1304, logrus stayed only to forward logs from docker/cli and moby/go-archive. The runner used a small part of those: volume parsing, the build context tar, the `ssh://` connection and registry credentials. Own code that matches them replaces them, so logrus leaves the module graph. docker/cli stays for its logrus-free `opts` and `connhelper/ssh` packages.

Other dependencies that the standard library or existing ones cover go too: mergo, httprouter (replaced by `http.ServeMux`), retry-go, go-isatty, go-selinux, container-device-interface, gotest.tools and go-cmp (replaced by testify). The binary shrinks by 5%.

Behaviour differences:

1. An unreadable file in a build context is skipped with a warning, where go-archive left a truncated tar.
2. Build contexts no longer carry `security.capability` xattrs.
3. The cache and artifact servers answer HEAD on GET routes, and no longer redirect trailing slashes or answer OPTIONS.

*Written by Claude.*

---------

Co-authored-by: bircni <[email protected]>
Reviewed-on: https://gitea.com/gitea/runner/pulls/1319
Reviewed-by: bircni <[email protected]>
Reviewed-by: Lunny Xiao <[email protected]>
Co-authored-by: silverwind <[email protected]>

act/container/docker_auth_test.go

@@ -0,0 +1,46 @@
+// Copyright 2026 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+//go:build !windows && !(WITHOUT_DOCKER || !(linux || darwin || netbsd))
+
+package container
+
+import (
+	"encoding/base64"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/moby/moby/api/types/registry"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestLoadDockerAuthConfigFromFileHelpersAndEnv(t *testing.T) {
+	dir := t.TempDir()
+	require.NoError(t, os.WriteFile(filepath.Join(dir, "docker-credential-fake"), []byte("#!/bin/sh\nread -r server\n[ \"$1\" = get ] && [ \"$server\" = helper.example.com ] && exec echo '{\"Username\":\"helped\",\"Secret\":\"pw\"}'\necho 'credentials not found in native keychain'\nexit 1\n"), 0o755))
+	t.Setenv("PATH", dir+string(os.PathListSeparator)+os.Getenv("PATH"))
+	auth := func(credentials string) string { return base64.StdEncoding.EncodeToString([]byte(credentials)) }
+	require.NoError(t, os.WriteFile(filepath.Join(dir, "config.json"), []byte(`{"auths": {"https://legacy.example.com/v1/": {"auth": "`+auth("legacy:pw")+`"}}, "credHelpers": {"helper.example.com": "fake", "gone.example.com": "fake", "env-legacy.example.com": ""}}`), 0o600))
+	t.Setenv("DOCKER_CONFIG", dir)
+	t.Setenv("DOCKER_AUTH_CONFIG", `{"auths": {"env.example.com": {"auth": "`+auth("env:pw")+`"}, "https://env-legacy.example.com/v1/": {"auth": "`+auth("env:pw")+`"}}}`)
+
+	for image, want := range map[string]registry.AuthConfig{
+		"legacy.example.com/app": {Username: "legacy", Password: "pw", ServerAddress: "https://legacy.example.com/v1/"},
+		"helper.example.com/app": {Username: "helped", Password: "pw", ServerAddress: "helper.example.com"},
+		"env.example.com/app":    {Username: "env", Password: "pw", ServerAddress: "env.example.com"},
+		"gone.example.com/app":   {},
+	} {
+		got, err := LoadDockerAuthConfig(t.Context(), image)
+		require.NoError(t, err)
+		assert.Equal(t, want, got, image)
+	}
+	assert.Equal(t, map[string]registry.AuthConfig{
+		"https://legacy.example.com/v1/":     {Username: "legacy", Password: "pw", ServerAddress: "https://legacy.example.com/v1/"},
+		"helper.example.com":                 {Username: "helped", Password: "pw", ServerAddress: "helper.example.com"},
+		"gone.example.com":                   {},
+		"env.example.com":                    {Username: "env", Password: "pw", ServerAddress: "env.example.com"},
+		"https://env-legacy.example.com/v1/": {Username: "env", Password: "pw", ServerAddress: "https://env-legacy.example.com/v1/"},
+		"env-legacy.example.com":             {Username: "env", Password: "pw", ServerAddress: "https://env-legacy.example.com/v1/"},
+	}, LoadDockerAuthConfigs(t.Context()))
+}