fix(vesktop): avoid DTLS stalls with multiple interfaces (#66)

* fix(vesktop): add WebRTC IP handling support

* fix(vesktop): constrain WebRTC interface selection

modules/applications/discord/home.nix

@@ -1,7 +1,19 @@
-_: {
+{
+  lib,
+  pkgs,
+  ...
+}: {
   programs.vesktop = {
     enable = true;
 
+    package =
+      if pkgs.stdenv.hostPlatform.isLinux then
+        pkgs.vesktop.overrideAttrs (old: {
+          patches = (old.patches or [ ]) ++ [ ./vesktop-webrtc-ip-handling-policy.patch ];
+        })
+      else
+        pkgs.vesktop;
+
     settings = {
       discordBranch = "stable";
 
@@ -16,6 +28,10 @@ _: {
 
       openLinksWithElectron = false;
 
+      # Keep WebRTC on interfaces used by the default route. Vesktop's default
+      # policy may select secondary private interfaces and stall at DTLS.
+      webRTCIPHandlingPolicy = "default_public_and_private_interfaces";
+
       spellCheckLanguages = [
         "ja-JP"
         "en-US"