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/testdata/host-report.golden.json

@@ -141,7 +141,8 @@
     ],
     "pbs": {
       "repo_id": "felhom-pbs",
-      "namespace": "root",
+      "namespace": "felhom-spike",
+      "namespace_state": "resolved",
       "latest_snapshot_id": "9001"
     },
     "drives": [
@@ -154,7 +155,13 @@
     ],
     "pve_storage": [
       { "name": "local-lvm", "type": "lvmthin", "content": "rootdir,images" },
-      { "name": "usb-backup", "type": "usb", "content": "backup" }
-    ]
+      { "name": "usb-backup", "type": "usb", "content": "backup" },
+      { "name": "felhom-pbs", "type": "pbs", "content": "backup" }
+    ],
+    "backup_target": {
+      "state": "resolved",
+      "storage_id": "usb-backup",
+      "mount_path": "/mnt/usb-backup"
+    }
   }
 }