R-106 + R-109: the DR recipe records the resolved namespace and names the backup target (v0.118.0)

Both defects were live on both demo boxes: the recipe said namespace "root" while
storage.cfg said demo-felhom/demo-hp, and it never named which of two content=backup
dir storages holds the local archives.

R-106: the namespace came from the listed snapshot, but PBS omits `ns` per item once
the list is namespace-scoped, so it was always empty and normalised to "root". It now
resolves from the pbs STORAGE (storage.cfg's `namespace`) — the same field vzdump makes
PVE read, so the recipe cannot disagree with the backup.

R-109: backup_target resolves from the primary tier of cfg.Backup.BackupTiers(), the
function the scheduler consults, and carries the mountpoint that separates /mnt/hdd_1
from /var/lib/vz. The resolver reports the tier IN EFFECT (daemon-start config), not
agent.json on disk — a target move rewrites the file and deliberately does not restart.

Unresolvable is recorded as unresolvable: resolved|unknown plus a distinct reason,
never a default, an empty string, or a placeholder.

Needs hub v0.83.0 — AssembleDRRecipe allow-lists top-level keys, so backup_target
would otherwise be stored intact and dropped before any operator saw it.

9 tests, 4 red-proofs (each mutation asserted to have landed). Suite rc=0, 29 ok.

internal/hub/report_test.go

@@ -35,7 +35,7 @@ func TestHostReport_FieldNamesAndEmptyCollections(t *testing.T) {
 	}
 	// dr_recipe is always set on the real path (Collect); set it here too so the "no null" invariant
 	// covers it (empty pbs is omitempty → omitted, never null).
-	r.DRRecipe = BuildDRRecipeHostHalf(r.Guests, r.StorageTargets, r.PBSSnapshots)
+	r.DRRecipe = BuildDRRecipeHostHalf(r.Guests, r.StorageTargets, r.PBSSnapshots, ConfiguredBackupTarget{})
 	b, err := json.Marshal(r)
 	if err != nil {
 		t.Fatal(err)