feat: add hold-to-talk listener and restore Handy-managed preferences

modules/capabilities/handy.nix

@@ -1,30 +1,16 @@
 {
+  flake.modules.nixos.handy = { pkgs, ... }: {
+    services.udev.packages = [
+      (pkgs.writeTextDir "lib/udev/rules.d/70-handy-keyboard.rules" ''
+        SUBSYSTEM=="input", KERNEL=="event*", ENV{ID_INPUT_KEYBOARD}=="1", TAG+="uaccess"
+      '')
+    ];
+  };
+
   flake.modules.homeManager.handy =
-    { config, pkgs, ... }:
+    { pkgs, ... }:
     let
-      settings = (pkgs.formats.json { }).generate "handy-settings.json" {
-        settings = {
-          settings_schema_version = 1;
-          selected_model = "handy-computer/nemotron-3.5-asr-streaming-0.6b-gguf/nemotron-3.5-asr-streaming-0.6b-Q8_0.gguf";
-          selected_language = "auto";
-          translate_to_english = false;
-          selected_microphone = null;
-          always_on_microphone = false;
-          push_to_talk = true;
-          paste_method = "ctrl_shift_v";
-          typing_tool = "wtype";
-          clipboard_handling = "dont_modify";
-          auto_submit = false;
-          overlay_style = "live";
-          overlay_position = "bottom";
-          post_process_enabled = false;
-          start_hidden = true;
-          autostart_enabled = false;
-          update_checks_enabled = false;
-          show_whats_new_on_update = false;
-          onboarding_completed = true;
-        };
-      };
+      python = pkgs.python3.withPackages (ps: [ ps.evdev ]);
     in
     {
       home.packages = [ pkgs.handy ];
@@ -37,10 +23,18 @@
         };
         Install.WantedBy = [ "graphical-session.target" ];
         Service = {
-          # Handy writes migrations and runtime preferences: restore the Nix baseline on start.
-          ExecStartPre = "${pkgs.coreutils}/bin/install -Dm600 ${settings} ${config.xdg.dataHome}/com.pais.handy/settings_store.json";
           ExecStart = "${pkgs.handy}/bin/handy --start-hidden";
         };
       };
+
+      systemd.user.services.handy-ptt = {
+        Unit = {
+          Description = "Handy push-to-talk key release listener";
+          PartOf = [ "graphical-session.target" ];
+          Requisite = [ "handy.service" ];
+          After = [ "handy.service" ];
+        };
+        Service.ExecStart = "${python}/bin/python ${./handy/_push_to_talk.py} ${pkgs.handy}/bin/handy";
+      };
     };
 }