hub v0.110.0: allowlist + operator-only for offsite_proof_empty (R-87)

Controller v0.231.0 adds a nightly job that proves an app's newest off-site snapshot still
CONTAINS that app's data. When it finds one that does not, it emits offsite_proof_empty.

Two register lines, both load-bearing and both in this commit:
- allowedEventTypes - an unallowlisted type is answered 400 and VANISHES, so this entry is
  what makes the alarm exist at all.
- operatorOnlyEvents - a missing customerMessages entry is NOT a routing block
  (FormatCustomerEmail falls back to the raw message, the v0.78.0 defect that register was
  built for). A customer can take no action on a hollow recovery unit.

DELIBERATELY NOT reusing backup_integrity_failed, which is the nearest existing type: it
means THE STORE IS DAMAGED and carries the Hungarian template saying so. Here the store is
sound and the CONTENT is absent - different cause, different action, and telling a customer
their backups are damaged when they are not is the more expensive mistake. Same asymmetry
looksLikeRepositoryDamage is shaped around.

DELIBERATELY no customerMessages entry (the controller's dynamic Hungarian names the app and
what is missing; a template would discard it) and DELIBERATELY not in perAppCooldownEvents
(a fenced act - this job proves ONE app per night, so the coarse hourly cooldown is already
the right grain).

This widens the R-87 task's stated repo scope to felhom.eu/hub/. The reason is recorded in
felhom-controller/CONTEXT.md ruling 4 rather than left as an unexplained diff.

Hub green gate: go build/vet/test all pass, 18 packages.

scripts/wire_contract_gate.py

@@ -171,6 +171,43 @@ ALLOWLIST = {
         "that card. The sibling `offsite.last_integrity_check` is NOT allowlisted and passes on its "
         "own — the string already occurs hub-side. **When a hub surface is built, delete this entry.**"),
 
+    # ---- R-87, controller v0.231.0: the nightly off-site PROOF's verdict ----
+    #
+    # Five fields, ONE reason, and it is the SAME reason as the two integrity siblings below: the
+    # verdict is published so a hub surface can read it, and no hub surface reads it yet. R-331 ruled
+    # that class a decision for the operator rather than something to fold into a controller task —
+    # the previous integrity card was REMOVED because it rendered a verdict for every customer
+    # forever from fields nothing wrote. Publishing first and consuming when someone decides what the
+    # screen should say is the opposite order to the one that produced that card.
+    #
+    # They are listed INDIVIDUALLY rather than as a prefix, so deleting them one at a time as a
+    # surface starts reading them is a reviewable diff. **Delete each entry when its field is read.**
+    # Filed with the integrity pair under R-402.
+    (_CH, "offsite.last_proof_result"): (
+        "R-87, controller v0.231.0: the nightly off-site content-proof VERDICT (pass / fail / "
+        "cannot_judge). Published for a hub surface that does not exist yet — same class and same "
+        "ruling as offsite.last_integrity_ok below (R-331, R-402). ABSENT means NOT RECORDED (a "
+        "controller older than v0.231.0), never 'failed', so any future reader must degrade to "
+        "unknown. **Delete this entry when a hub surface reads it.**"),
+    (_CH, "offsite.last_proof_reason"): (
+        "R-87: the machine reason code behind the verdict above (e.g. database_expected_none_captured). "
+        "Unconsumed for the identical reason. It matters because 'fail' alone cannot distinguish a "
+        "backup that is readable-and-empty from one whose manifest could not be read, and those are "
+        "different operator actions. **Delete with its siblings.**"),
+    (_CH, "offsite.last_proof_stack"): (
+        "R-87: WHICH app the newest verdict is about. One app is proved per night, so a verdict "
+        "without its app names nothing. Unconsumed for the same reason. **Delete with its siblings.**"),
+    (_CH, "offsite.last_proof_snapshot"): (
+        "R-87: WHICH SNAPSHOT was proved — the per-archive due-ness model (R-86, 07 §3) records the "
+        "snapshot and never a timestamp, and a hub surface showing the verdict without it cannot say "
+        "whether the newest backup was the one proved. Unconsumed for the same reason. **Delete with "
+        "its siblings.**"),
+    (_CH, "offsite.last_proof_run"): (
+        "R-87: when that verdict was reached. Unconsumed for the same reason. NOTE for whoever builds "
+        "the surface: this is an attempt-free stamp — it is written ONLY when a verdict was actually "
+        "reached, never on a skip, a missing snapshot or a restore error, so 'presence is not success' "
+        "does not bite here. **Delete with its siblings.**"),
+
     (_CH, "offsite.last_integrity_depth"): (
         "R-399, controller v0.228.0: the DEPTH the verdict was reached at, published beside "
         "last_integrity_ok above and unconsumed for the identical reason. It matters because 'checked, "