v0.98.0 — R-82 Slice A fix: per-tier vzdump wait bound (the 30-minute false failure)

Found by live validation on demo-felhom, not by review.

The first real PBS-targeted backup ran past the runner's hard-coded 30-minute
WaitTask bound. The agent stopped waiting and recorded success=false WHILE THE
VZDUMP KEPT RUNNING (still running 72 min later, 2.4 GB uploaded). Consequences:
the tier stays permanently due, the next attempt collides with the guest lock
the live vzdump holds, and the hub sees a DR tier that never succeeds — R-82's
'applied and empty' fault re-created by a timeout.

Measured: ~33 MB/min over wg to Hetzner, so a first FULL ~10 GB snapshot
projects to ~5h.

- BackupTargetConfig.WaitTimeoutSeconds: per-tier bound. Primary 30m UNCHANGED
  (a local vzdump hanging 30m IS a real fault); additional tier 6h, sized from
  the measurement.
- backup.NewBackupRunnerWithWait: per-instance (per-tier) bound.
  NewBackupRunner keeps its signature, so restore-test/selftest are untouched.
- localapi.BackupTier.WaitTimeout: the fire-and-forget context is sized from the
  tier, not a fixed 2h. BOTH bounds had to move — a 6h runner bound under a 2h
  outer context reproduces the same false failure four hours later.

Same direction as restore_test_pbs_restore_timeout_seconds: when in doubt wait
LONGER. A slow backup is a slow backup; a false timeout is a corrupt status
plus lock contention.

Red-proof observed and restored; full suite green.

internal/localapi/backup_tiers.go

@@ -24,13 +24,16 @@ func normalizeBackupTiers(tiers []BackupTier, legacy BackupService, cadence time
 		if t.Cadence <= 0 {
 			t.Cadence = cadence
 		}
+		if t.WaitTimeout <= 0 {
+			t.WaitTimeout = 2 * time.Hour
+		}
 		usable = append(usable, t)
 	}
 	if len(usable) == 0 {
 		if legacy == nil {
 			return nil
 		}
-		return []BackupTier{{TargetID: "", Cadence: cadence, Primary: true, Service: legacy}}
+		return []BackupTier{{TargetID: "", Cadence: cadence, WaitTimeout: 2 * time.Hour, Primary: true, Service: legacy}}
 	}
 	primary := -1
 	for i, t := range usable {