R-553: four decisions stop reading their own Hungarian words (sites 1-4)

Every Hungarian sentence is byte-identical; each decision now reads a signal set where the message is
made. util.KindErrorf builds the same bytes fmt.Errorf did while carrying a sentinel for errors.Is.

- Deploy status (api/router.go): deployStatusFor() by kind — stacks.ErrAlreadyDeployed (409),
  ErrRequiredField / ErrPathMissing / ErrNotEnoughMemory (400). The „kötelező" / „memória" /
  "does not exist" / "already deployed" text chain is gone.
- Off-site failure class (backup/offbox.go): ErrOffsiteQuota replaces the „tárhelykeretet" match. The
  restic/ssh signatures stay text matches on purpose — that output is not ours and is not translated.
- Alert placement (web/alerts.go): monitor.HealthReport carries WarningKinds parallel to Warnings;
  the "not on a separate drive" warning is inline by KIND. The hub report is untouched (builder.go
  copies Status/Issues/Warnings only) — pinned by a wire test.
- Stale off-site note (web/handlers.go): settings LastWarningKind + backup.OffboxWarnNoAppsSelected.
  The text test survives ONLY for kind == "" (a box whose last run predates 0.251.0) and is removed
  when R-570 closes; slice 2 must not translate that producer before then.

Tests (all red-proofed by restoring the pre-fix predicate — see the audit's redproofs.txt):
TestR553_Deploy_DecisionSurvivesWordingChange, TestR553_DeployHandlerUsesTheKind,
TestR553_DeployProducersCarryKindAndKeepTheirWords (through the real DeployStack),
TestR553_OffsiteQuota_{Decision,HeadLine}SurvivesWordingChange, TestR553_OffboxRunRecordsTheKind,
TestR553_StorageWarningsCarryKindsAndKeepTheirWords, TestR553_DiskWarningPlacementSurvivesWordingChange,
TestR553_HubReportWarningsAreUnchangedOnTheWire, TestR553_StaleNote*, TestR553_WarningKindIsPersistedAndCopied.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0159rPz1ZhFKsS53msqPYxtS

controller/internal/web/offbox_handlers.go

@@ -100,7 +100,7 @@ func (s *Server) offboxConfigHandler(w http.ResponseWriter, r *http.Request) {
 		// succeeded" on a routine settings save. Pinned by TestOffboxEdit_PreservesLastSuccess.
 		tgt.LastSuccess = prev.LastSuccess
 		tgt.LastDuration, tgt.RepoSizeHuman, tgt.SnapshotCount = prev.LastDuration, prev.RepoSizeHuman, prev.SnapshotCount
-		tgt.LastWarning = prev.LastWarning
+		tgt.LastWarning, tgt.LastWarningKind = prev.LastWarning, prev.LastWarningKind
 		tgt.EscrowState = prev.EscrowState
 		tgt.RepoSizeBytes = prev.RepoSizeBytes
 		tgt.StatsKnown = prev.StatsKnown // R-225: preserved with the numbers it qualifies