Add DNS filtering with dnsmasq address=/ directives for wildcard blocking

Adds Pi-hole-style DNS filtering using dnsmasq's native address=/ directives,
which block domains and all subdomains. Users subscribe to blocklists by URL
or upload files, with suggested lists from Hagezi, Steven Black, and OISD.
Background runner refreshes lists on a configurable interval (default 24h).

web/src/router/pages/DnsFilterPage.tsx

@@ -0,0 +1,10 @@
+import { ErrorBoundary } from '../../components';
+import { DnsFilterComponent } from '../../components/DnsFilterComponent';
+
+export function DnsFilterPage() {
+  return (
+    <ErrorBoundary>
+      <DnsFilterComponent />
+    </ErrorBoundary>
+  );
+}