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>

docs/api.md

@@ -471,6 +471,7 @@ written in Jarl's fixed order (docs/concepts.md).
 | GET | `/catalog/options` | scopes and zone types; with `?scope=options\|view\|toplevel\|zone:primary\|...` every statement allowed there (name, grammar, kind, status, ARM description). `?all=1` includes statements Jarl manages itself |
 | GET | `/catalog/rrtypes` | record types with field hints and examples |
 | GET | `/catalog/grants` | resources, roles and the grant syntax |
+| GET | `/exposure` | which views are reachable from the internet, the exposure findings and their fixes ([exposure.md](exposure.md#api)); `POST /exposure/fix`, `/exposure/ack`, `/exposure/unack` |
 | GET | `/catalog/ranges?r=A-B,C-D` | for each address range: `range` (canonical), `size` ("99 addresses"), and the `prefixes` it is written to named.conf as; or `error`. Text that isn't a range is left out |
 | GET | `/search?q=text` | zones, records and ACLs matching the text |