Add blocking: blocklists and block/allow rules with BIND response policy zones

jarld downloads blocklists (Adblock, hosts or plain domains), checks them
daily and reloads named only when a list changed; your own block and
allow rules take precedence, and the most specific rule wins. Lists and
rules apply per view (default: every view that offers recursion). Web UI
Blocking page with name checks, jarl blocklist and jarl block, the
/blocking API, blocked counts in the statistics. Database schema 6.

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

README.md

@@ -71,6 +71,10 @@ error: www.adbraun.lol has a CNAME, so it can't have any other records (found A)
   queries, record types, cache hit rate. Shown in the web UI and the CLI,
   and exportable as JSON. Stored as aggregates in a separate database with
   retention you set.
+* **Blocking** like Pi-hole, done by named itself: blocklists (Adblock,
+  hosts or plain domains) downloaded and kept up to date, your own block
+  and allow rules that beat every list, per view, with "why is this
+  blocked?" checks and blocked counts in the statistics.
 * **Let's Encrypt DNS-01** built in: `jarl acme` plus certbot, acme.sh and lego
   hooks, an HTTPS-only endpoint for lego's and Traefik's `httpreq` provider,
   and CNAME delegation to a dedicated ACME zone.
@@ -116,6 +120,7 @@ in `/etc/jarl/jarl.yaml` to reach it from your management network.
 | [docs/dnssec.md](docs/dnssec.md) | DNSSEC signing, going public with your own name servers, Porkbun |
 | [docs/acme.md](docs/acme.md) | Let's Encrypt DNS-01 with certbot, acme.sh, lego and Traefik |
 | [docs/stats.md](docs/stats.md) | Query statistics: enabling, what is collected, retention |
+| [docs/blocking.md](docs/blocking.md) | Blocking ads, trackers and malware: blocklists, your own rules, views, memory |
 | [docs/validation.md](docs/validation.md) | Every check Jarl makes |
 | [docs/operations.md](docs/operations.md) | Backups, drift, failures, recovery, monitoring |
 | [docs/development.md](docs/development.md) | Code layout, tests against real BIND, conventions |