Disable records instead of deleting them

A disabled record stays in Jarl with its ID, TTL and comment but is
left out of the zone; the zone file lists it as a comment. Web UI
toggle, jarl record disable|enable, record.disable|enable operations
and API endpoints. Database schema 5.

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

internal/validate/validate.go

@@ -115,13 +115,14 @@ type checker struct {
 	opts     Options
 	problems []Problem
 	// indexes
-	zoneRecords map[int64][]*model.Record
+	zoneRecords map[int64][]*model.Record // served records (not disabled)
+	allRecords  map[int64][]*model.Record
 	keyNames    map[string]bool
 }
 
 // State validates the complete state.
 func State(s *model.State, opts Options) []Problem {
-	c := &checker{s: s, opts: opts, zoneRecords: s.RecordsByZone(), keyNames: map[string]bool{}}
+	c := &checker{s: s, opts: opts, zoneRecords: s.ServedRecordsByZone(), allRecords: s.RecordsByZone(), keyNames: map[string]bool{}}
 	for _, k := range s.Keys {
 		c.keyNames[k.Name] = true
 	}