feat(xray/dns): align DNS settings with Xray docs + UI polish

- DNS server modal: rename expectIPs -> expectedIPs (per docs); add
  per-server tag, clientIP, serveStale, serveExpiredTTL, timeoutMs;
  flip skipFallback default to false; hydration still accepts legacy
  expectIPs for back-compat.
- DNS tab: add hosts editor (domain -> IP/array), serveStale +
  serveExpiredTTL controls, "Use Preset" button bringing back the
  legacy preset gallery (Google / Cloudflare / AdGuard + Family
  variants — fixed AdGuard Family IPs that were wrong in legacy),
  and a "Delete All" button to wipe the server list at once.
- i18n: add 15 new dns.* keys across all 13 locales.
- Frontend-wide formatter pass on Vue components (whitespace and
  attribute layout only, no behavior changes).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

web/translation/en-US.json

@@ -752,9 +752,24 @@
         "unexpectIPs": "Unexpect IPs",
         "useSystemHosts": "Use System Hosts",
         "useSystemHostsDesc": "Use the hosts file from an installed system",
+        "serveStale": "Serve Stale",
+        "serveStaleDesc": "Return expired cached results while refreshing in the background",
+        "serveExpiredTTL": "Serve Expired TTL",
+        "serveExpiredTTLDesc": "Validity (seconds) of stale cache entries; 0 = never expire",
+        "timeoutMs": "Timeout (ms)",
+        "skipFallback": "Skip Fallback",
+        "finalQuery": "Final Query",
+        "hosts": "Hosts",
+        "hostsAdd": "Add Host",
+        "hostsEmpty": "No host overrides defined",
+        "hostsDomain": "Domain (e.g. domain:example.com)",
+        "hostsValues": "IP or domain — type and press Enter",
         "usePreset": "Use Preset",
         "dnsPresetTitle": "DNS Presets",
-        "dnsPresetFamily": "Family"
+        "dnsPresetFamily": "Family",
+        "clearAll": "Delete All",
+        "clearAllTitle": "Delete all DNS servers?",
+        "clearAllConfirm": "This removes every DNS server from the list. This cannot be undone."
       },
       "fakedns": {
         "add": "Add Fake DNS",