feat: add netbird for homelab, keep tailscale for work (#225)

modules/nixos/desktop/networking/netbird.nix

@@ -0,0 +1,38 @@
+{
+  lib,
+  pkgs,
+  ...
+}:
+# =============================================================
+#
+# NetBird - your own private network(VPN) that uses WireGuard, Coturn, etc.
+#
+# It's similar to tailscale, but netbird's more opensouse and less mature.
+#
+# NetBird natively supports running multiple clients on the same host — something
+#   Tailscale can’t do easily.
+# Its NixOS module ships a dedicated CLI wrapper for every client, so managing them is effortless.
+#
+# How to use:
+#  1. Create a NetBird account at https://app.netbird.io/
+#  3. Login & join into your homelab network via `netbird-homelab up`
+#
+# Status Data:
+#   `journalctl -u netbird-homelab` shows netbird's logs
+#   netbird client store its data in /var/lib/netbird-homelab
+#   which is already persistent across reboots(via preservation)
+#
+# References:
+#  https://github.com/NixOS/nixpkgs/blob/nixos-unstable/nixos/modules/services/networking/netbird.nix
+#
+# =============================================================
+{
+  services.netbird.useRoutingFeatures = "client";
+  services.netbird.clients.homelab = {
+    port = 51820;
+    name = "homelab";
+    interface = "netbird-homelab";
+    hardened = true;
+    autoStart = true;
+  };
+}