Fix zone list filtering and BIND warning display; add a views guide

- jarl zone list showed only primary zones. zone create binds its --type
  flag (default "primary") to the same variable as list's --type, so the
  default leaked into the list filter and hid hint, secondary and forward
  zones. list now has its own variable. TestListQueries runs list
  commands against a fake server and checks the filters they send.
- named-checkconf/named-checkzone messages are classified by the tool's
  exit code: on success, everything printed is a warning. Warnings such
  as 'both "recursion no;" and "allow-recursion" active' were shown as
  errors. The CLI, jarld check and the web UI now label them as warnings
  and skip the routine "loaded serial" lines.
- The zone_outside_view error points at --adopt-zones.
- docs/views.md: step-by-step split DNS for a server that has no views
  yet, tested on a copy of a stock Ubuntu 26.04 setup. Linked from the
  README, concepts and validation docs.

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

docs/validation.md

@@ -52,7 +52,7 @@ showing them.
 | `wildcard_unusual` | warning | Wildcard NS records |
 | `soa_invalid`, `soa_warning`, `ttl_invalid` | error / warning | SOA fields and TTLs in range and sensible. One warning covers negative caching longer than 3 hours: resolvers cache "no such name" answers for the smaller of the SOA minimum and the zone's default TTL (RFC 2308), so a new name can stay invisible that long. 1 hour (`--minimum 3600`) is a good value |
 | `zone_name_invalid`, `zone_type_invalid`, `zone_duplicate` | error | Valid zone names and types. A zone exists once per view |
-| `zone_outside_view` | error | Once views exist, every zone must be in one (named requires this) |
+| `zone_outside_view` | error | Once views exist, every zone must be in one (named requires this). Create the first view with `--adopt-zones` to move all zones into it ([views.md](views.md)) |
 | `zone_missing_option` | error | Secondary, stub and mirror zones need `primaries` |
 | `zone_file_required` / `zone_file_invalid` / `zone_file_managed` | error | Hint zones need a file. Forward zones have none. Primary zone files are Jarl's |
 | `zone_inview_invalid`, `zone_inview_option` | error | `in-view` zones only inside views, and only with `forward`/`forwarders` |