Refactoring complete: v0.4.0 architectural milestone (#1)

## Summary

Completed Phase 5 refactoring and reached the target architecture.

**Architectural milestone achieved:**
- Service layer owns all state and is the sole writer
- UI is a thin Fyne view, all widget updates marshaled via `fyne.Do`
- Core engines are stateless and injectable
- Domain types are pure (no `yaml:"-"` fields)
- Full module builds and `go vet ./...` clean

## Changes

- Bump version: 0.3.6 → 0.4.0
- Update CHANGELOG with Phase 5 summary
- Add ROADMAP "Refactoring Follow-Ups" section

## Known follow-up work

1. **Linux test build broken** — `runner_test.go` needs `//go:build windows` tag
2. **File-size limits exceeded** — `operations.go` (486 lines), `jobs_view.go` (415 lines)

See ROADMAP.md for details.

---------

Co-authored-by: mixeme <mix.public@ya.ru>
Reviewed-on: #1

src/app/format_test.go

@@ -0,0 +1,109 @@
+package app
+
+import (
+	"testing"
+
+	"gitea.mixdep.ru/mix/gosentry/src/domain"
+)
+
+func TestStatusText(t *testing.T) {
+	tests := []struct {
+		name    string
+		job     domain.Job
+		runtime *domain.JobRuntime
+		want    string
+	}{
+		{"disabled is paused", domain.Job{Enabled: false}, &domain.JobRuntime{LastState: "Running"}, "Paused"},
+		{"enabled shows runtime state", domain.Job{Enabled: true}, &domain.JobRuntime{LastState: "Success"}, "Success"},
+		{"enabled with nil runtime is empty", domain.Job{Enabled: true}, nil, ""},
+	}
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			if got := StatusText(tc.job, tc.runtime); got != tc.want {
+				t.Errorf("StatusText = %q, want %q", got, tc.want)
+			}
+		})
+	}
+}
+
+func TestEventText(t *testing.T) {
+	withLog := domain.RunRecord{
+		Time: "2026-06-19 12:00:00", Trigger: "Schedule", JobName: "Build",
+		State: "Success", Detail: "ok", LogFile: "build.log",
+	}
+	if got, want := EventText(withLog), "2026-06-19 12:00:00  Schedule  Build  Success  ok  build.log"; got != want {
+		t.Errorf("EventText with log = %q, want %q", got, want)
+	}
+
+	noLog := domain.RunRecord{
+		Time: "2026-06-19 12:00:00", Trigger: "Manual", JobName: "Build",
+		State: "Success", Detail: "ok",
+	}
+	if got, want := EventText(noLog), "2026-06-19 12:00:00  Manual  Build  Success  ok"; got != want {
+		t.Errorf("EventText without log = %q, want %q", got, want)
+	}
+
+	// An empty trigger is shown as "Unknown".
+	blank := domain.RunRecord{Time: "t", JobName: "J", State: "S", Detail: "d"}
+	if got, want := EventText(blank), "t  Unknown  J  S  d"; got != want {
+		t.Errorf("EventText blank trigger = %q, want %q", got, want)
+	}
+}
+
+func TestDisplayFolder(t *testing.T) {
+	if got := DisplayFolder("   "); got != "(No folder)" {
+		t.Errorf("blank folder = %q, want %q", got, "(No folder)")
+	}
+	if got := DisplayFolder("  Reports  "); got != "Reports" {
+		t.Errorf("folder = %q, want %q", got, "Reports")
+	}
+}
+
+func TestDisplayArguments(t *testing.T) {
+	if got := DisplayArguments(""); got != "(none)" {
+		t.Errorf("empty args = %q, want %q", got, "(none)")
+	}
+	if got := DisplayArguments("  -v  "); got != "-v" {
+		t.Errorf("args = %q, want %q", got, "-v")
+	}
+}
+
+func TestDisplaySuccessExitCodes(t *testing.T) {
+	if got := DisplaySuccessExitCodes("  "); got != "0" {
+		t.Errorf("empty codes = %q, want %q", got, "0")
+	}
+	if got := DisplaySuccessExitCodes(" 0,1 "); got != "0,1" {
+		t.Errorf("codes = %q, want %q", got, "0,1")
+	}
+}
+
+func TestDisplayRunMode(t *testing.T) {
+	if got := DisplayRunMode(domain.Job{StartOnly: true}); got != "Start only" {
+		t.Errorf("start-only = %q, want %q", got, "Start only")
+	}
+	if got := DisplayRunMode(domain.Job{StartOnly: false}); got != "Wait for completion" {
+		t.Errorf("wait = %q, want %q", got, "Wait for completion")
+	}
+}
+
+func TestDisplayInvocation(t *testing.T) {
+	if got := DisplayInvocation(domain.Job{Command: "echo"}); got != "echo" {
+		t.Errorf("no args = %q, want %q", got, "echo")
+	}
+	// Arguments are appended with spacing and their newlines collapsed to spaces.
+	job := domain.Job{Command: "echo", Arguments: "  hi\nthere  "}
+	if got, want := DisplayInvocation(job), "echo    hi there"; got != want {
+		t.Errorf("with args = %q, want %q", got, want)
+	}
+}
+
+func TestDisplayIndex(t *testing.T) {
+	indexes := []int{4, 7, 2}
+	if got := DisplayIndex(indexes, 7); got != 1 {
+		t.Errorf("DisplayIndex(7) = %d, want 1", got)
+	}
+	// A jobIndex not present returns 0.
+	if got := DisplayIndex(indexes, 99); got != 0 {
+		t.Errorf("DisplayIndex(missing) = %d, want 0", got)
+	}
+}