Show egress/ingress levels in the registry; freeze checks at the verdict

Registry: the "last result" column now also shows, per level (egress,
ingress), how many of the recorded checks of the latest cycle succeeded, split
by check family (tcp-22 and tcp-443 are both "tcp"). One grouped query per
chunk of addresses; new fields last_cycle_id, egress, ingress in
GET /admin/registry; the dashboard renders them under the verdict.

Verdict integrity (migration 0010):
- the prober is handed an address once per site and attempt, not on every
  poll, so results are no longer overwritten by later probe rounds;
- UpsertCheckIfOpen refuses writes once the address is aggregating or has its
  verdict, or for an older attempt; senders get {"ok":true,"ignored":N} and a
  result_dropped event is recorded;
- the checking window counts from checking_started_at, not from assigned_at;
- checks.recorded_at (server clock) and checks.after_verdict (flag for rows
  written after the verdict in existing data);
- the verdict rule is a pure function (computeVerdict) and the aggregated
  event carries the egress/ingress check counts.

Rebuilt bin/control-api and bin/admin-dashboard to match. Plans and summaries
are in docs/changes; README, API, USAGE, DASHBOARD and DIAGRAMS are updated.

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

internal/httpapi/handlers_agent.go

@@ -149,6 +149,7 @@ func (s *Server) handleAgentResults(w http.ResponseWriter, r *http.Request) {
 		writeError(w, http.StatusBadRequest, "invalid body: "+err.Error())
 		return
 	}
+	dropped := map[int64]int{}
 	for _, res := range req.Results {
 		item, err := s.DB.GetIP(r.Context(), res.IPID)
 		if err != nil {
@@ -159,7 +160,7 @@ func (s *Server) handleAgentResults(w http.ResponseWriter, r *http.Request) {
 		if err != nil {
 			checkedAt = db.Now()
 		}
-		err = s.Orch.RecordCheck(r.Context(), db.Check{
+		written, err := s.Orch.RecordCheckIfOpen(r.Context(), db.Check{
 			IPID: item.ID, IPAddress: item.IPAddress, AttemptNumber: item.AttemptNumber,
 			ValidatorID: id, Source: db.SourceEgress, CheckType: res.CheckType, Target: res.Target,
 			Success: res.Success, LatencyMS: res.LatencyMS, Detail: res.Detail, CheckedAt: checkedAt,
@@ -168,8 +169,11 @@ func (s *Server) handleAgentResults(w http.ResponseWriter, r *http.Request) {
 			writeError(w, http.StatusInternalServerError, err.Error())
 			return
 		}
+		if !written {
+			dropped[item.ID]++
+		}
 	}
-	writeJSON(w, http.StatusOK, okResponse{OK: true})
+	writeJSON(w, http.StatusOK, s.reportDropped(r.Context(), "validator-agent", id, db.SourceEgress, dropped))
 }
 
 func (s *Server) handleAgentComplete(w http.ResponseWriter, r *http.Request) {