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>

internal/validate/zones.go

@@ -43,7 +43,7 @@ func (c *checker) checkZones() {
 			continue
 		}
 		if hasViews && z.ViewID == 0 {
-			c.zoneProblem(z, Error, "zone_outside_view", "when views are used, every zone must be inside a view (named requires this); move the zone into a view")
+			c.zoneProblem(z, Error, "zone_outside_view", "when views are used, every zone must be inside a view (named requires this); move the zone into a view, or create the first view with adopt_zones (jarl view create NAME --adopt-zones) to move all zones at once")
 		}
 		if err := dnsname.CheckZoneName(z.Name); err != nil {
 			c.zoneProblem(z, Error, "zone_name_invalid", "invalid zone name: %v", err)