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.go

@@ -0,0 +1,89 @@
+package app
+
+import (
+	"fmt"
+	"strings"
+
+	"gitea.mixdep.ru/mix/gosentry/src/domain"
+)
+
+// StatusText formats a job's current state for display: "Paused" if disabled,
+// else its runtime LastState (Ready, Running, Success, etc).
+func StatusText(j domain.Job, runtime *domain.JobRuntime) string {
+	if !j.Enabled {
+		return "Paused"
+	}
+	if runtime == nil {
+		return ""
+	}
+	return runtime.LastState
+}
+
+// EventText formats a run record for the History table, showing time, trigger,
+// job name, outcome state, detail, and log file (if any).
+func EventText(e domain.RunRecord) string {
+	trigger := e.Trigger
+	if trigger == "" {
+		trigger = "Unknown"
+	}
+	if e.LogFile != "" {
+		return fmt.Sprintf("%s  %s  %s  %s  %s  %s", e.Time, trigger, e.JobName, e.State, e.Detail, e.LogFile)
+	}
+	return fmt.Sprintf("%s  %s  %s  %s  %s", e.Time, trigger, e.JobName, e.State, e.Detail)
+}
+
+// DisplayFolder formats a job's folder for display: "(No folder)" if empty,
+// else the trimmed folder name.
+func DisplayFolder(folder string) string {
+	if strings.TrimSpace(folder) == "" {
+		return "(No folder)"
+	}
+	return strings.TrimSpace(folder)
+}
+
+// DisplayArguments formats a job's arguments for display: "(none)" if empty,
+// else the trimmed arguments.
+func DisplayArguments(arguments string) string {
+	if strings.TrimSpace(arguments) == "" {
+		return "(none)"
+	}
+	return strings.TrimSpace(arguments)
+}
+
+// DisplaySuccessExitCodes formats a job's success exit codes for display:
+// "0" (the default) if empty, else the trimmed codes.
+func DisplaySuccessExitCodes(codes string) string {
+	if strings.TrimSpace(codes) == "" {
+		return "0"
+	}
+	return strings.TrimSpace(codes)
+}
+
+// DisplayRunMode formats a job's execution mode: "Start only" or
+// "Wait for completion".
+func DisplayRunMode(job domain.Job) string {
+	if job.StartOnly {
+		return "Start only"
+	}
+	return "Wait for completion"
+}
+
+// DisplayInvocation formats a job's command and arguments for the jobs list,
+// joining them with spacing and collapsing newlines in arguments to spaces.
+func DisplayInvocation(job domain.Job) string {
+	if strings.TrimSpace(job.Arguments) == "" {
+		return job.Command
+	}
+	return job.Command + "    " + strings.ReplaceAll(strings.TrimSpace(job.Arguments), "\n", " ")
+}
+
+// DisplayIndex returns the position of jobIndex in the given slice of indexes,
+// or 0 if not found.
+func DisplayIndex(indexes []int, jobIndex int) int {
+	for display, index := range indexes {
+		if index == jobIndex {
+			return display
+		}
+	}
+	return 0
+}