Remove the ConfigMap, RPZ and managed-directory editors the cluster objects replace

Zones, address redirects, inline rules, lists and groups are cluster objects now
(see the previous commits and deploy/MIGRATION.md), so the mechanisms that held
them are gone:

* internal/kubezones and the resolver's service-account access to a ConfigMap,
  the address-overrides read/write path and its poller, the zone-file poller and
  the Local zones editor with its /api/local-zones routes.
* localzone.Managed, the directory of console-written master files, and the
  blocklist.managed_zones key. The resolver now writes no zone data at all; its
  zone hooks only list. The shared half of that file (the record validator, the
  renderer and the round-trip check) stays as zonestate.go, because DNSZone
  rendering is built on it. Its tests are ported to RenderZone, which keeps the
  coverage of every editable record type, wildcards, relative owners, the
  SOA/NS rule and the delegation rule.
* Tests of the removed write paths: the contract test now builds its zone from a
  DNSZone, and a new test pins that every zone write route on the resolver is
  refused and changes nothing.

Standalone installs keep editing master files on disk and SIGHUP, and the
YAML-backed domain, client, upstream and settings editors, which have not moved.

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

internal/config/config.go

@@ -316,15 +316,6 @@ type Block struct {
 	// LocalZones are DNS master files (RFC 1035) holding RPZ-style policy
 	// records and/or locally defined zones.
 	LocalZones []string `yaml:"local_zones"`
-	// ManagedZones is the directory the admin API may write local zone
-	// files into: one <apex>.zone per zone, holding the SOA, the apex NS
-	// set and whatever records the console created. It is the only zone
-	// data the console owns — the files in LocalZones are the operator's and
-	// are reported read-only.
-	//
-	// Empty means the console's zone pages are read-only, so a deployment
-	// that never sets it cannot have zone data rewritten behind its back.
-	ManagedZones string `yaml:"managed_zones"`
 	// Lists are remote or on-disk sources of block data.
 	Lists []ListSource `yaml:"lists"`
 	// AllowEntries and BlockEntries are inline rules (a list of DNS names or