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/validation.md

@@ -124,11 +124,26 @@ From [blocking.md](blocking.md).
 
 ## Security lints
 
+These and the exposure checks below only look at views that are
+reachable from the internet ([exposure.md](exposure.md)); without views,
+the open resolver and open transfer checks look at the server. Any of them
+can be acknowledged (it then shows as info, with who accepted it and why),
+and a change that newly introduces an open resolver, open transfers, cache
+snooping, open NOTIFY or an open management interface on a public view
+must be confirmed (`--accept-risk`).
+
 | Code | Severity | What it catches |
 |------|----------|-----------------|
 | `security_open_resolver` | warning | A view (or the server) where recursion is on and reachable by any client. This includes the BIND trap where `allow-recursion` is unset and inherits `allow-query { any; }`. Open resolvers are abused for DDoS amplification. Set `allow-recursion` to your own networks |
 | `security_open_transfer` | warning | `allow-transfer` open to anyone. Restrict it to your secondaries or a TSIG key |
 | `dynamic_update_unsupported` | error | `allow-update` / `update-policy` on a Jarl zone. named would write to files that Jarl regenerates, losing the updates. Use the API (e.g. `jarl acme`) instead |
+| `exposure_rate_limit` | warning | A public view without response rate limiting (`rate-limit`) |
+| `exposure_rate_limit_log_only` | info | Rate limiting in log-only mode: check what it would limit, then enforce |
+| `exposure_minimal_any` | warning | A public view answering ANY queries in full (`minimal-any` off) |
+| `exposure_cache_snooping` | warning | A public view without recursion whose cache anyone may query (`allow-query-cache`) |
+| `exposure_open_notify` | warning | A public view accepting NOTIFY from anyone (`allow-notify`) |
+| `exposure_version`, `exposure_hostname` | warning | The server is public and shows its BIND version or host name to anyone (`version none`, `hostname none`) |
+| `exposure_management` | warning | `controls` or `statistics-channels` on an address that isn't loopback, open to anyone, while the server is public |
 
 ## What only BIND checks