Internet exposure checks and response rate limiting

Jarl works out which views are reachable from the internet (match-clients
ending in a catch-all, not private-looking addresses: an internal view of a
global IPv6 prefix is still yours; a server without views: open allow-query
and a non-private listen address), with a per-view override (schema 9), and
checks public ones: rate limiting, open resolver, minimal-any, cache
snooping, open NOTIFY and transfers, version and host name, management
interfaces. Fixes are staged like any change, including rate limiting from
ISC's example in log-only mode with the secondaries exempt, then enforcing.
named logs what rate limiting limits (or would, in log-only mode, where its
counters don't move) as query-errors; Jarl routes those lines to its log
and counts them (rrl breakdown, ratelimited top lists, Prometheus
jarl_ratelimit_logged_total), shown on the new Exposure page.

A change that newly opens a public view up must be confirmed (accept_risk,
--accept-risk, a checkbox on the Changes page; 409 confirm_risk
otherwise). Findings can be acknowledged with a reason and stay visible as
info. GET /exposure, POST /exposure/fix|ack|unack, jarl exposure,
docs/exposure.md.

Also fixes query statistics skipping TSIG-signed queries ("IP#port/key
NAME" in named's log).

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

internal/engine/diffops.go

@@ -3,6 +3,7 @@ package engine
 import (
 	"fmt"
 	"reflect"
+	"slices"
 	"sort"
 
 	"jarl/internal/dnsname"
@@ -23,7 +24,8 @@ func DiffOps(from, to *model.State) []model.Op {
 	if !reflect.DeepEqual(stripVersion(from.Settings), stripVersion(to.Settings)) {
 		s := to.Settings
 		add(OpSettingsUpdate, 0, 0, SettingsInput{DefaultTTL: &s.DefaultTTL, Nameservers: model.Ptr(append([]string{}, s.Nameservers...)), RName: &s.RName,
-			Refresh: &s.Refresh, Retry: &s.Retry, Expire: &s.Expire, NegativeTTL: &s.NegativeTTL, SerialPolicy: &s.SerialPolicy}, "restore settings")
+			Refresh: &s.Refresh, Retry: &s.Retry, Expire: &s.Expire, NegativeTTL: &s.NegativeTTL, SerialPolicy: &s.SerialPolicy,
+			Exposure: &s.Exposure, Acknowledged: model.Ptr(slices.Clone(s.Acknowledged))}, "restore settings")
 	}
 
 	for _, k := range sortedKeys(to.Keys) {
@@ -47,7 +49,8 @@ func DiffOps(from, to *model.State) []model.Op {
 	for _, k := range sortedKeys(to.Views) {
 		n := to.Views[k]
 		in := ViewInput{Name: &n.Name, MatchClients: model.Ptr(append([]string{}, n.MatchClients...)),
-			MatchDestinations: model.Ptr(append([]string{}, n.MatchDestinations...)), Comment: &n.Comment, Position: model.Ptr(n.Position)}
+			MatchDestinations: model.Ptr(append([]string{}, n.MatchDestinations...)), Comment: &n.Comment, Position: model.Ptr(n.Position),
+			Exposure: model.Ptr(n.Exposure), Acknowledged: model.Ptr(slices.Clone(n.Acknowledged))}
 		if n.MatchRecursiveOnly != nil {
 			in.MatchRecursiveOnly = model.Some(*n.MatchRecursiveOnly)
 		} else {