Add blocking: blocklists and block/allow rules with BIND response policy zones

jarld downloads blocklists (Adblock, hosts or plain domains), checks them
daily and reloads named only when a list changed; your own block and
allow rules take precedence, and the most specific rule wins. Lists and
rules apply per view (default: every view that offers recursion). Web UI
Blocking page with name checks, jarl blocklist and jarl block, the
/blocking API, blocked counts in the statistics. Database schema 6.

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

internal/api/types.go

@@ -242,6 +242,17 @@ type StatusResponse struct {
 	Backup *BackupStatus `json:"backup,omitempty"`
 	// TOTP is about two-factor login across users (administrators only).
 	TOTP *TOTPOverview `json:"totp,omitempty"`
+	// BlocklistErrors are blocklists whose last update failed (for those
+	// who may see blocking).
+	BlocklistErrors []BlocklistError `json:"blocklist_errors,omitempty"`
+}
+
+// BlocklistError is a blocklist whose last update failed. UpdatedAt is
+// the version named keeps using (nil: none yet).
+type BlocklistError struct {
+	Name      string     `json:"name"`
+	Error     string     `json:"error"`
+	UpdatedAt *time.Time `json:"updated_at,omitempty"`
 }
 
 // TOTPOverview is what the dashboard reports about two-factor login.
@@ -471,3 +482,28 @@ type RegistrarChangeResponse struct {
 	Checks   []nscheck.Finding `json:"checks"`
 	Warnings []string          `json:"warnings"`
 }
+
+// Blocklist is a blocklist as returned by the API (docs/blocking.md).
+type Blocklist struct {
+	model.Blocklist
+	// Views are the views it applies to; AutoViews is set when that is
+	// "every view that offers recursion" (view_ids is empty).
+	Views     []string `json:"views"`
+	AutoViews bool     `json:"auto_views,omitempty"`
+	// State is ok, waiting (not downloaded yet), error (the last update
+	// failed; the previous version stays in use), disabled, or idle (it
+	// applies to no view).
+	State  string                 `json:"state"`
+	Status *model.BlocklistStatus `json:"status,omitempty"`
+	// MemoryMB estimates what named needs for the list, in all its views.
+	MemoryMB int    `json:"memory_mb,omitempty"`
+	Pending  string `json:"pending,omitempty"`
+}
+
+// BlockRule is a block or allow rule as returned by the API.
+type BlockRule struct {
+	model.BlockRule
+	Views     []string `json:"views"`
+	AutoViews bool     `json:"auto_views,omitempty"`
+	Pending   string   `json:"pending,omitempty"`
+}