Add dns_txt, webrtc_mesh, and wsus_cache_peer LOTL deploy tiers with Forge toggles.

Implements three new spread lanes following the do_peer pattern: DNS TXT mesh staging, WebRTC LAN seed manifest delivery, and WSUS SoftwareDistribution cousin handoff. Integrates tiers into onion chain, deploy-plan allowlist, Forge UI/docs, and tests.

server/web/src/pages/SettingsPage.tsx

@@ -34,7 +34,6 @@ import {
   buildDefenderExclusionScript,
   defaultWindowsInstallPreview,
 } from '../help/defenderExclusion';
-import './Pages.css';
 
 /** Recursively merge `override` into `base`, preserving keys not in `override`. */
 export function deepMerge<T extends object>(base: T, override: Partial<T>): T {