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/dashboard/render.go

@@ -2,6 +2,7 @@ package dashboard
 
 import (
 	"errors"
+	"fmt"
 	"html/template"
 	"net/http"
 	"strconv"
@@ -115,6 +116,24 @@ var funcMap = template.FuncMap{
 	"join":        strings.Join,
 	"joinInts":    joinInts,
 	"pluralAddr":  pluralAddr,
+	"dict":        dict,
+}
+
+// dict builds a map from alternating key/value arguments, so a sub-template
+// can be given several values: {{template "x" dict "Name" .A "L" .B}}.
+func dict(kv ...any) (map[string]any, error) {
+	if len(kv)%2 != 0 {
+		return nil, fmt.Errorf("dict: odd number of arguments")
+	}
+	m := make(map[string]any, len(kv)/2)
+	for i := 0; i < len(kv); i += 2 {
+		k, ok := kv[i].(string)
+		if !ok {
+			return nil, fmt.Errorf("dict: key %v is not a string", kv[i])
+		}
+		m[k] = kv[i+1]
+	}
+	return m, nil
 }
 
 // pluralAddr returns the correctly declined Russian word for "address"