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/backup/runner.go

@@ -38,21 +38,34 @@ type BackupRunner struct {
 	// each successful backup, so the agent's own backups can't pile up and refill root. Empty → no prune
 	// (the legacy behaviour; restore-test/selftest runners pass ""). NEVER applied to a PBS target.
 	retention string
-	logger    *slog.Logger
-	now       func() time.Time
+	// waitTimeout bounds the WaitTask poll on this runner's vzdump. Per-TIER since R-82: 30m is
+	// right for a local vzdump and badly wrong for an offsite PBS upload (see the 2026-07-26 live
+	// failure recorded on config.BackupTargetConfig.WaitTimeoutSeconds). 0 → 30m (legacy).
+	waitTimeout time.Duration
+	logger      *slog.Logger
+	now         func() time.Time
 }
 
 // NewBackupRunner builds a runner. mode defaults to snapshot (works for a stopped guest and
 // for lvm-thin); the caller may pass ModeStop for storages without snapshot support. retention is the
 // per-run prune spec ("keep-last=N", or "" to never prune) — only the periodic local backup sets it.
 func NewBackupRunner(api BackupAPI, target string, mode proxmox.BackupMode, notes, retention string, logger *slog.Logger) *BackupRunner {
+	return NewBackupRunnerWithWait(api, target, mode, notes, retention, 0, logger)
+}
+
+// NewBackupRunnerWithWait is NewBackupRunner plus an explicit vzdump wait bound (0 → 30m).
+func NewBackupRunnerWithWait(api BackupAPI, target string, mode proxmox.BackupMode, notes, retention string, waitTimeout time.Duration, logger *slog.Logger) *BackupRunner {
 	if mode == "" {
 		mode = proxmox.ModeSnapshot
 	}
 	if logger == nil {
 		logger = slog.Default()
 	}
-	return &BackupRunner{api: api, target: target, mode: mode, notes: notes, retention: retention, logger: logger, now: func() time.Time { return time.Now().UTC() }}
+	if waitTimeout <= 0 {
+		waitTimeout = 30 * time.Minute
+	}
+	return &BackupRunner{api: api, target: target, mode: mode, notes: notes, retention: retention,
+		waitTimeout: waitTimeout, logger: logger, now: func() time.Time { return time.Now().UTC() }}
 }
 
 // localPruneSpec returns the `--prune-backups` spec to apply to THIS backup, or "" to skip pruning. It
@@ -147,7 +160,7 @@ func (r *BackupRunner) backup(ctx context.Context, vmid int, onSnapshot func())
 			defer stopWatch()
 			go r.watchForSnapshot(watchCtx, upid, onSnapshot)
 		}
-		if _, err := r.api.WaitTask(ctx, upid, proxmox.WaitOptions{Timeout: 30 * time.Minute}); err != nil {
+		if _, err := r.api.WaitTask(ctx, upid, proxmox.WaitOptions{Timeout: r.waitTimeout}); err != nil {
 			rec.Error = err.Error()
 			rec.DurationSeconds = time.Since(start).Seconds()
 			return rec, fmt.Errorf("backup: vzdump task vmid %d: %w", vmid, err)