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/help/fleetGroups.test.ts

@@ -29,7 +29,7 @@ describe('fleetGroups', () => {
 
   it('groupsForAgent and primaryGroupForAgent', () => {
     const groups = [
-      createFleetGroup('G1', '#00f5ff', ['x']),
+      createFleetGroup('G1', '#00e8f5', ['x']),
       createFleetGroup('G2', '#ff0000', ['x', 'y']),
     ];
     expect(groupsForAgent(groups, 'x').map((g) => g.name)).toEqual(['G1', 'G2']);