enhance: report a GitHub-style "Set up job" section (#1089)

Reshapes the job log's "Set up job" section to mirror `actions/runner`:

- runner name/version, then `Runner Information` (labels, task, job, repository, event) and `Operating System` groups
- every required action downloaded up front under `Prepare all required actions`, each as `Download action repository '<action>@<ref>' (SHA:<sha>)`
- `Complete job name` closes the section

Downloading up front is the one behavioral change: the same set was already fetched during the pre stage regardless of a step's `if`, now just before the first pre step, so a download failure is reported against the job rather than a step.

---------

Co-authored-by: silverwind <me@silverwind.io>
Reviewed-on: https://gitea.com/gitea/runner/pulls/1089
Reviewed-by: silverwind <2021+silverwind@noreply.gitea.com>

internal/app/run/setup.go

@@ -0,0 +1,83 @@
+// Copyright 2026 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package run
+
+import (
+	"fmt"
+	"os"
+	"runtime"
+	"strconv"
+	"strings"
+
+	"gitea.com/gitea/runner/internal/pkg/report"
+	"gitea.com/gitea/runner/internal/pkg/ver"
+
+	runnerv1 "gitea.dev/actions-proto-go/runner/v1"
+)
+
+// osReleasePath describes the host distribution on Linux; absent elsewhere, where the platform
+// falls back to the Go runtime alone. A var so tests can point it at a fixture.
+var osReleasePath = "/etc/os-release"
+
+// reportSetup opens the job log the way actions/runner opens its "Set up job" step. The action
+// downloads and the closing job name are written later, as the job starts.
+func (r *Runner) reportSetup(reporter *report.Reporter, task *runnerv1.Task) {
+	for _, line := range r.setupLines(task) {
+		reporter.Logf("%s", line)
+	}
+}
+
+// setupLines names the runner, then reports what it was asked to run and the host it runs on, each
+// in its own group.
+func (r *Runner) setupLines(task *runnerv1.Task) []string {
+	fields := task.Context.Fields
+	lines := []string{
+		fmt.Sprintf("%s(version:%s)", r.name, ver.Version()),
+		"::group::Runner Information",
+	}
+	if names := r.labels.Names(); len(names) > 0 {
+		lines = append(lines, "Runner labels: "+strings.Join(names, ", "))
+	}
+	lines = append(lines,
+		// The task id correlates the job log with the runner's log and the server's task list.
+		fmt.Sprintf("Task: %d", task.Id),
+		"Job: "+fields["job"].GetStringValue(),
+		"Repository: "+fields["repository"].GetStringValue(),
+		"Triggered by event: "+fields["event_name"].GetStringValue(),
+		"::endgroup::",
+		"::group::Operating System",
+	)
+	lines = append(lines, osInfo()...)
+	return append(lines, "::endgroup::")
+}
+
+// osInfo describes the host the runner executes on.
+func osInfo() []string {
+	lines := make([]string, 0, 2)
+	if name := prettyOSName(); name != "" {
+		lines = append(lines, name)
+	}
+	return append(lines, fmt.Sprintf("%s/%s", runtime.GOOS, runtime.GOARCH))
+}
+
+// prettyOSName reads PRETTY_NAME (e.g. "Ubuntu 24.04.4 LTS") from os-release, or "" when absent.
+func prettyOSName() string {
+	data, err := os.ReadFile(osReleasePath)
+	if err != nil {
+		return ""
+	}
+
+	for line := range strings.SplitSeq(string(data), "\n") {
+		key, value, ok := strings.Cut(strings.TrimSpace(line), "=")
+		if !ok || key != "PRETTY_NAME" {
+			continue
+		}
+		// Values are shell-quoted, but the quotes are optional.
+		if unquoted, err := strconv.Unquote(value); err == nil {
+			return unquoted
+		}
+		return value
+	}
+	return ""
+}