zoom: allow meeting links to open in the main zoom session

hosts/common/programs/zoom-us.nix

@@ -1,12 +1,17 @@
-{ ... }:
+{ pkgs, ... }:
 {
   sane.programs.zoom-us = {
+    packageUnwrapped = pkgs.zoom-us.override {
+      xdgDesktopPortalSupport = true;  #< what does this do? who knows!
+    };
     sandbox.net = "clearnet";
     sandbox.whitelistAudio = true;
     sandbox.whitelistAvDev = true;  #< XXX(2025-05-29): it doesn't use pipewire for mic/video
     sandbox.whitelistDri = true;
     sandbox.whitelistWayland = true;
     sandbox.whitelistX = true;  # XXX(2025-05-29): required; TODO: try setting QP_... env vars to get native wayland?
+    sandbox.tmpDir = ".zoom";  #< tmpdir needs to be shared between instances, for the singleton socket to work (also, it needs to exist)
+    mime.associations."x-scheme-handler/zoommtg" = "Zoom.desktop";  #< for when you click on a meeting link
     # TODO: .config/{zoom,zoomus}.conf
     # TODO: .config/Unknown Organization/zoom.conf
     persist.byStore.ephemeral = [