fix(nix): Fix dev shell on macOS

Signed-off-by: Steffen Vogel <post@steffenvogel.de>

nix/cunicu.nix

@@ -69,7 +69,7 @@ buildGo124Module {
     description = "Zeroconf peer-to-peer mesh VPN using Wireguard and Interactive Connectivity Establishment (ICE)";
     homepage = "https://cunicu.li";
     license = lib.licenses.asl20;
-    platforms = lib.platforms.linux;
+    platforms = lib.platforms.linux ++ lib.platforms.darwin;
     maintainers = [ lib.maintainers.stv0g ];
     mainProgram = "cunicu";
   };

nix/shell.nix

@@ -2,6 +2,8 @@
 # SPDX-FileCopyrightText: 2025 Steffen Vogel <post@steffenvogel.de>
 # SPDX-License-Identifier: Apache-2.0
 {
+  lib,
+  stdenv,
   mkShell,
 
   act,
@@ -25,23 +27,26 @@
   ...
 }:
 mkShell {
-  packages = [
-    act
-    coturn
-    evans
-    ginkgo
-    gnumake
-    gocov-merger
-    golangci-lint
-    goreleaser
-    inotify-tools
-    libpcap
-    nix-update
-    reuse
-    svu
+  packages =
+    [
+      act
+      evans
+      ginkgo
+      gnumake
+      gocov-merger
+      golangci-lint
+      goreleaser
+      libpcap
+      nix-update
+      reuse
+      svu
 
-    cunicu-scripts
-  ];
+      cunicu-scripts
+    ]
+    ++ lib.optional stdenv.isLinux [
+      coturn
+      inotify-tools
+    ];
 
   inputsFrom = [
     cunicu