fix: escape command data the runner writes itself (#1120)

Command data is percent-escaped on the wire because Gitea's job log cannot carry a newline, and the renderer decodes it.

1. Unescaping iterated a map, so order was random per process: `%250A` decoded to a newline instead of a literal `%0A` about two runs in three. Now a precompiled `strings.NewReplacer`.
1. Escape the data of command lines the runner writes itself (`##[error]`, `::group::Run …`), so decoding returns the original text instead of mangling a `%`. Multi-line runner errors also get real line breaks instead of a literal `\n`.
1. Register secrets in escaped form too — one containing `%` reaches the log as `%25…` and was never masked.
1. Decode in `jobLogFormatter`, so `gitea-runner exec` matches the web view.

## Relation to the Gitea PR

https://github.com/go-gitea/gitea/pull/38659 makes the renderer decode command data. Point 2 is required by it; the rest stand alone. Either order works — until both land, a new runner on old Gitea shows `%25`, an old runner on new Gitea shows the mangling point 2 fixes.
Co-authored-by: bircni <bircni@icloud.com>
Reviewed-on: https://gitea.com/gitea/runner/pulls/1120
Reviewed-by: bircni <bircni@icloud.com>
Co-authored-by: silverwind <me@silverwind.io>

act/runner/logger_test.go

@@ -4,11 +4,13 @@
 package runner
 
 import (
+	"io"
 	"strings"
 	"testing"
 
 	"github.com/sirupsen/logrus"
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 func TestValueMasker(t *testing.T) {
@@ -33,6 +35,12 @@ func TestValueMasker(t *testing.T) {
 			masks:      []string{"PRIVATE_KEY_BEGIN\ndsdfseffefsefes\ndsdfseffefsefes\ndsdfseffefsefes\ndsdfseffefsefes\ndsdfseffefsefes\ndsdfseffefsefes\ndsdfseffefsefes\ndsdfseffefsefes\ndsdfseffefsefes\nPRIVATE_KEY_END"},
 			disallowed: []string{"KEY", "dsdfseffefsefes", "PRIVATE_KEY_END"},
 		},
+		{
+			name:       "Secret containing a percent sign",
+			lines:      "##[error]login failed for pass%25word",
+			secrets:    map[string]string{"TOKEN": "pass%word"},
+			disallowed: []string{"pass%25word"},
+		},
 	}
 	for _, entry := range table {
 		t.Run(entry.name, func(t *testing.T) {
@@ -50,3 +58,17 @@ func TestValueMasker(t *testing.T) {
 		})
 	}
 }
+
+func TestJobLogFormatterDecodesCommandData(t *testing.T) {
+	logger := logrus.New()
+	logger.Out = io.Discard
+	format := func(message string) string {
+		out, err := (&jobLogFormatter{}).Format(&logrus.Entry{Logger: logger, Message: message, Data: logrus.Fields{rawOutputField: true}})
+		require.NoError(t, err)
+		return string(out)
+	}
+
+	assert.Contains(t, format("##[error]deploy 50%25 traffic"), "##[error]deploy 50% traffic")
+	// a plain line is not command data and keeps its literal escapes
+	assert.Contains(t, format("progress 50%25 done"), "progress 50%25 done")
+}