Phase B: Agent registers routes with mc-proxy on deploy

The agent connects to mc-proxy via Unix socket and automatically
registers/removes routes during deploy and stop. This eliminates
manual mcproxyctl usage or TOML editing.

- New ProxyRouter abstraction wraps mc-proxy client library
- Deploy: after container starts, registers routes with mc-proxy
  using host ports from the registry
- Stop: removes routes from mc-proxy before stopping container
- Config: [mcproxy] section with socket path and cert_dir
- Nil-safe: if mc-proxy socket not configured, route registration
  is silently skipped (backward compatible)
- L7 routes use certs from convention path (<cert_dir>/<service>.pem)
- L4 routes use TLS passthrough (backend_tls=true)

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

vendor/git.wntrmute.dev/kyle/mc-proxy/client/mcproxy/doc.go

@@ -0,0 +1,41 @@
+// Package mcproxy provides a Go client for the mc-proxy gRPC admin API.
+//
+// The client connects to mc-proxy via Unix socket and provides methods
+// for managing routes, firewall rules, and querying server status.
+//
+// # Basic Usage
+//
+//	client, err := mcproxy.Dial("/srv/mc-proxy/mc-proxy.sock")
+//	if err != nil {
+//	    log.Fatal(err)
+//	}
+//	defer client.Close()
+//
+//	// Get server status
+//	status, err := client.GetStatus(ctx)
+//	if err != nil {
+//	    log.Fatal(err)
+//	}
+//	fmt.Printf("mc-proxy %s, %d connections\n", status.Version, status.TotalConnections)
+//
+//	// List routes for a listener
+//	routes, err := client.ListRoutes(ctx, ":443")
+//	if err != nil {
+//	    log.Fatal(err)
+//	}
+//	for _, r := range routes {
+//	    fmt.Printf("  %s -> %s\n", r.Hostname, r.Backend)
+//	}
+//
+//	// Add a route
+//	err = client.AddRoute(ctx, ":443", "example.com", "127.0.0.1:8443")
+//
+//	// Add a firewall rule
+//	err = client.AddFirewallRule(ctx, mcproxy.FirewallRuleCIDR, "10.0.0.0/8")
+//
+//	// Check health
+//	health, err := client.CheckHealth(ctx)
+//	if health == mcproxy.HealthServing {
+//	    fmt.Println("Server is healthy")
+//	}
+package mcproxy