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/api/types.go

@@ -19,9 +19,11 @@ const Prefix = "/api/v1"
 // Zone is a zone as returned by the API.
 type Zone struct {
 	model.Zone
-	Display  string `json:"display_name"`
-	View     string `json:"view,omitempty"`
-	Records  int    `json:"record_count"`
+	Display string `json:"display_name"`
+	View    string `json:"view,omitempty"`
+	Records int    `json:"record_count"`
+	// Disabled is how many of the records are disabled.
+	Disabled int    `json:"disabled_count,omitempty"`
 	ZoneFile string `json:"zone_file,omitempty"` // the file named loads
 	RName    string `json:"rname_email,omitempty"`
 	// Registrar names the registrar Jarl can manage the domain at
@@ -40,7 +42,8 @@ type Record struct {
 	EffectiveTTL uint32 `json:"effective_ttl"`
 	// Text is the decoded value of TXT and SPF records.
 	Text *string `json:"text,omitempty"`
-	// Pending is set when listing with a changeset: add, change or delete.
+	// Pending is set when listing with a changeset: add, change, delete,
+	// disable or enable.
 	Pending string `json:"pending,omitempty"`
 }