R-195: a customer with no machine ever bound does not alarm (hub v0.92.0) + R-193/R-192 spike

Part 4 (ships): `david` — a prospective customer with hosts=0, host_deletions=0,
reports=0 — e-mailed an expected_dbdump_missed ERROR at 03:00 UTC three mornings
running. The existing down-skip could never cover it: it reads the staleness
checker's state, which is seeded from a query over the `reports` table, so a
customer that never reported has no state at all and GetState() returns "" rather
than "down". store.HasEverBoundHost (hosts row OR host_deletions tombstone) is
consulted once per customer at the top of the deadline loop. The discriminator is
"was a host EVER bound", never "has a report arrived" — a box installed and never
heard from is a real fault and keeps alarming. Fail-OPEN on a read error. Red-proof
observed: removing the guard fails with `got [expected_dbdump_missed]`, verbatim the
event david sent.

Parts 0-3 (spike, NO production code for R-193/R-192):
audits/SPIKE-offsite-credential-recovery-2026-08-04.md establishes that the one-shot
provider password is the RECOVERABLE secret and the restic repository password is the
irreplaceable one — and that a guest rebuild mints a fresh one, orphaning the previous
off-site history. Measured without touching a box, by comparing
host_escrow.restic_pw_sha256 against host_escrow_superseded: BOTH demo boxes changed
(demo-hp 15 snapshots / 40.9 MB, demo-felhom 36 snapshots / 1.14 GB). demo-felhom's
"lucky" 76-second recovery restored delivery and not the repository, silently, for 13h.
ReissueCredentials does NOT rotate the restic password (R-39's record and two hub
comments are wrong -> R-196); candidate (b) is not implementable against a
zero-knowledge escrow; candidate (a) already exists as F3 and is wired to the wrong
event. Ends in ranked options and an unanswered question for the operator.

R-195 SHIPPED; R-196 + R-197 filed; R-192 + R-193 updated, neither closed.

hub/internal/store/store.go

@@ -2262,6 +2262,28 @@ func (s *Store) GetHostByCustomer(customerID string) (*Host, error) {
 	return h, err
 }
 
+// HasEverBoundHost reports whether a machine was EVER bound to this customer — a live row in
+// `hosts` OR a tombstone in `host_deletions`. It answers "was anything ever expected of this
+// customer", which is the question the deadline verdicts actually need (R-195).
+//
+// It is deliberately NOT "has a report arrived", and the distinction is the whole point: a box
+// that was installed, bound, and then went silent IS bound, and its silence is a real fault that
+// must keep alarming. Only a customer that never had a machine at all is UNKNOWN.
+//
+// `host_deletions` is included because a customer whose host was removed HAD one — the deadline
+// caller reaches its down-skip for that shape, and this predicate must not quietly take over a
+// judgement the staleness checker owns.
+func (s *Store) HasEverBoundHost(customerID string) (bool, error) {
+	var n int
+	if err := s.db.QueryRow(
+		`SELECT EXISTS(SELECT 1 FROM hosts WHERE customer_id = ?)
+		     OR EXISTS(SELECT 1 FROM host_deletions WHERE customer_id = ?)`,
+		customerID, customerID).Scan(&n); err != nil {
+		return false, err
+	}
+	return n != 0, nil
+}
+
 // ListHostsByCustomer returns the customer's hosts ordered by host_id (v0.47.0 — the
 // customer page's Host tab is a LIST by design: 1 host today, N for a later HA cluster).
 // Uses the idx_hosts_customer index.