R-101 + F-DIAG: the restore dialog names the last SUCCESSFUL copy (v0.182.0)

Tier2LastRun is the attempt clock and was rendered as 'Legutóbbi másolat' in the restore
confirm dialog. New LastSuccess + SuccessTracked anchor; tier2Update makes the three
rebuild sites safe by construction. F-DIAG: six distinct causes, target-aware redaction.

controller/cmd/controller/main.go

@@ -654,8 +654,10 @@ func main() {
 		// error) alerts the operator via the allowlisted backup_failed event. Daily after Tier 2.
 		backupMgr.SetOffboxNotify(func(dur time.Duration, snapshots int, err error) {
 			if err != nil {
+				// F-DIAG: a distinct message per cause, and the detail SANITISED — a raw err.Error()
+				// carries the sftp:user@host:/path repo reference off the box.
 				notifier.NotifyBackupFailed("Off-box (NAS) mentés sikertelen",
-					"a NAS-ra mentés hibázott ("+dur.Round(time.Second).String()+"): "+err.Error())
+					backupMgr.OffsiteFailureMessage(err, dur))
 			}
 		})
 		// 3a: the pre-push enlargement gate blocked an app's userdata push (config+DB still saved). Edge-