reconcile: tier-aware restore-task deadline (S4.1 unattended offsite restore-test)

A WAN (pbs-tier) restore of a large guest exceeds the restore-task wait's 10m
default → the wait expired mid-restore, teardown fired against a still-restoring
(not-yet-pool-associated) scratch guest → leak + a phantom VM.Allocate 403.

- RestoreTestSpec.RestoreTaskTimeout (0→10m default); the restore WaitTask passes
  it. Local tier unchanged (10m).
- config RestoreTestPBSRestoreTimeoutSeconds + accessor (default 120m).
- main restoreTaskTimeout(cfg,tier): configured PBS timeout only when tier==pbs,
  else 0. Both scheduler + selftest spec builds.
- Tests + WaitOptions red-proof + accessor contract.

The "grant scratch-band VM.Allocate" follow-up is diagnosed not blind-applied:
the scratch is restored INTO /pool/felhom (ACL already grants VM.Allocate), so
the earlier 403 was a consequence of the timeout. No ACL/host-install change.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PSK5g6qYLknKj8u3QAFEr6

internal/config/config.go

@@ -198,6 +198,12 @@ type BackupConfig struct {
 	// always excluded. Defaults to 990000–990009.
 	ScratchVMIDMin int `json:"scratch_vmid_min"`
 	ScratchVMIDMax int `json:"scratch_vmid_max"`
+	// RestoreTestPBSRestoreTimeoutSeconds bounds the wait on a PBS-tier (offsite/WAN) restore-test
+	// restore task; 0 → default 120m. A large guest restored over a slow home uplink runs long, and
+	// for an UNATTENDED nightly test a false timeout (→ mid-restore teardown → leaked scratch) is
+	// worse than a slow pass. Very large guests may need a higher value. LOCAL-tier restores keep
+	// the 10m WaitOptions default (a local restore hanging 10m is a genuine fault).
+	RestoreTestPBSRestoreTimeoutSeconds int `json:"restore_test_pbs_restore_timeout_seconds"`
 
 	// PBS (slice 6 Phase B). The verify maintenance loop runs on its own cadence (cheaper +
 	// more frequent than the full restore-test); 0 → default (6h), negative → disabled.
@@ -245,6 +251,14 @@ func (b BackupConfig) BackupCadence() time.Duration {
 	return 24 * time.Hour
 }
 
+// RestoreTestPBSRestoreTimeout returns the PBS-tier restore-task wait: positive as-is, else 120m.
+func (b BackupConfig) RestoreTestPBSRestoreTimeout() time.Duration {
+	if b.RestoreTestPBSRestoreTimeoutSeconds > 0 {
+		return time.Duration(b.RestoreTestPBSRestoreTimeoutSeconds) * time.Second
+	}
+	return 120 * time.Minute
+}
+
 // defaultBackupTarget is the offsite PBS storage whole-guest backups land on by default. It is
 // SEPARATE HARDWARE from the guest's own disk (a PBS datastore on the DooPlex box), so a host
 // disk/hardware failure doesn't take the backups with it — that's what makes it real DR. Proven