Retry a failed self-check on another validator; add the self-check failure ceiling

A validator that failed the self-check of an address no longer gets that address
again in the current round (ClaimNextQueued skips it); the validator itself stays
in service and takes all other addresses. The verdict fail is set when the number
of failed self-checks of an address reaches settings.self_check_max_attempts
(1..50, default 5, independent of the number of validators); max_retries and
retry_count are no longer used for self-check. If every working validator has
already failed the address, a new round starts and the exclusions lapse.

Migration 0012: ip_self_check_failures (permanent history per registry address),
ip_queue.sc_failures and sc_round_start_cycle (cycle_id is used instead of
attempt_number, which restarts when a queue row is recreated), the setting.
db.FailSelfCheck does it in one transaction; re-submission starts a new series.
API: self_check_max_attempts in GET/PUT /admin/config/orchestrator,
self_check_failed_on in /admin/ips/{ip} and /admin/registry/{ip}. Dashboard: the
field on /settings and the line "Self-check не прошёл на: ..." on the address
pages. Docs, plan and summary in docs/changes/.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

internal/httpapi/handlers_registry.go

@@ -81,10 +81,17 @@ func (s *Server) handleAdminRegistryHistory(w http.ResponseWriter, r *http.Reque
 		writeError(w, http.StatusInternalServerError, err.Error())
 		return
 	}
+	// Self-check failures over every run of the address.
+	failedOn, err := s.DB.ListSelfCheckFailedOn(r.Context(), summary.ID, 0)
+	if err != nil {
+		writeError(w, http.StatusInternalServerError, err.Error())
+		return
+	}
 	writeJSON(w, http.StatusOK, struct {
-		Registry registryDTO `json:"registry"`
-		Checks   []db.Check  `json:"checks"`
-	}{registrySummaryToDTO(*summary), checks})
+		Registry          registryDTO `json:"registry"`
+		Checks            []db.Check  `json:"checks"`
+		SelfCheckFailedOn []string    `json:"self_check_failed_on"`
+	}{registrySummaryToDTO(*summary), checks, failedOn})
 }
 
 func registrySummaryToDTO(s db.RegistrySummary) registryDTO {