[self-hosted] add netbird server (#5232)

* Unified NetBird combined server (Management, Signal, Relay, STUN) as a single executable with richer YAML configuration, validation, and defaults.
  * Official Dockerfile/image for single-container deployment.
  * Optional in-process profiling endpoint for diagnostics.
  * Multiplexing to route HTTP/gRPC/WebSocket traffic via one port; runtime hooks to inject custom handlers.
* **Chores**
  * Updated deployment scripts, compose files, and reverse-proxy templates to target the combined server; added example configs and getting-started updates.

combined/cmd/pprof.go

@@ -0,0 +1,33 @@
+//go:build pprof
+// +build pprof
+
+package cmd
+
+import (
+	"net/http"
+	_ "net/http/pprof"
+	"os"
+
+	log "github.com/sirupsen/logrus"
+)
+
+func init() {
+	addr := pprofAddr()
+	go pprof(addr)
+}
+
+func pprofAddr() string {
+	listenAddr := os.Getenv("NB_PPROF_ADDR")
+	if listenAddr == "" {
+		return "localhost:6969"
+	}
+
+	return listenAddr
+}
+
+func pprof(listenAddr string) {
+	log.Infof("listening pprof on: %s\n", listenAddr)
+	if err := http.ListenAndServe(listenAddr, nil); err != nil {
+		log.Fatalf("Failed to start pprof: %v", err)
+	}
+}