Initial implementation of mc-proxy

Layer 4 TLS SNI proxy with global firewall (IP/CIDR/GeoIP blocking),
per-listener route tables, bidirectional TCP relay with half-close
propagation, and a gRPC admin API (routes, firewall, status) with
TLS/mTLS support.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

go.mod

@@ -0,0 +1,20 @@
+module git.wntrmute.dev/kyle/mc-proxy
+
+go 1.24.0
+
+require (
+	github.com/oschwald/maxminddb-golang v1.13.1
+	github.com/pelletier/go-toml/v2 v2.2.4
+	github.com/spf13/cobra v1.10.2
+	google.golang.org/grpc v1.79.2
+	google.golang.org/protobuf v1.36.11
+)
+
+require (
+	github.com/inconshreveable/mousetrap v1.1.0 // indirect
+	github.com/spf13/pflag v1.0.9 // indirect
+	golang.org/x/net v0.48.0 // indirect
+	golang.org/x/sys v0.39.0 // indirect
+	golang.org/x/text v0.32.0 // indirect
+	google.golang.org/genproto/googleapis/rpc v0.0.0-20251202230838-ff82c1b0f217 // indirect
+)