P1.5: drop SuccessExitCodes field and exit-code flexibility

Remove the SuccessExitCodes field from domain.Job and every layer that
read or wrote it: runner/exitcodes.go (deleted), runner.go runStateDetail
simplified to 0=OK / non-zero=Failed, logfile.go, format.go, operations.go,
store.go, job_dialog.go, and jobs_view.go. Tests updated accordingly.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/app/operations.go

@@ -436,8 +436,6 @@ func runningOutput(job domain.Job, trigger string, started time.Time) string {
 	builder.WriteString(job.Command + "\n\n")
 	builder.WriteString("arguments:\n")
 	builder.WriteString(runner.LogArguments(job.Arguments))
-	builder.WriteString("\n\nsuccess_exit_codes:\n")
-	builder.WriteString(runner.SuccessExitCodesText(job))
 	builder.WriteString("\n\nstart_only:\n")
 	builder.WriteString(fmt.Sprintf("%t", job.StartOnly))
 	return builder.String()
@@ -451,10 +449,6 @@ func normalizeJob(job *domain.Job) {
 	job.Schedule = strings.TrimSpace(job.Schedule)
 	job.Command = strings.TrimSpace(job.Command)
 	job.Arguments = strings.TrimSpace(job.Arguments)
-	job.SuccessExitCodes = strings.TrimSpace(job.SuccessExitCodes)
-	if job.SuccessExitCodes == "" {
-		job.SuccessExitCodes = "0"
-	}
 }
 
 // validateJob enforces the minimum executable definition: name, schedule, and