Add the Blacktip edge

The edge: per-IP TCP/UDP/HTTP/HTTPS/TLS listeners with port ranges and PROXY
protocol, WireGuard tunnel endpoint, logins in front of web ports (built-in
proxy or Traefik), health checks and failover, and mail egress with DKIM
signing and MTA-STS. Split out of the original single repository; depends on
Reef for the shared types.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

go.mod

@@ -0,0 +1,21 @@
+module git.veillax.com/Veillax/blacktip
+
+go 1.27.3
+
+require (
+	git.veillax.com/Veillax/reef v0.1.0
+	github.com/emersion/go-msgauth v0.7.0
+	golang.org/x/crypto v0.58.0
+)
+
+require (
+	github.com/Microsoft/go-winio v0.6.4 // indirect
+	github.com/google/btree v1.1.2 // indirect
+	golang.org/x/net v0.61.0 // indirect
+	golang.org/x/sys v0.49.0 // indirect
+	golang.org/x/text v0.43.0 // indirect
+	golang.org/x/time v0.7.0 // indirect
+	golang.zx2c4.com/wintun v0.0.0-20230126152724-0fa3db229ce2 // indirect
+	golang.zx2c4.com/wireguard v0.0.0-20261024220952-b3bc704ef0ee // indirect
+	gvisor.dev/gvisor v0.0.0-20250503011706-39ed1f5ac29c // indirect
+)