feat: SIGUSR2 handling for toggles, wayland enigo feature

[johnpyp]

This PR adds:

• support for sending SIGUSR2 to handy to toggle recording on and off,
  • This provides a robust way to handle keybinds centrally (in Wayland, for example) like discussed in [BUG] Wayland - Unable to trigger outside of Handy app #140, rather than going through the app.
• adds the wayland feature to enigo
  • this allows enigo to use the wayland input method protocol, which is supported by most wayland compositors.
  • with this feature enabled, enigo will still attempt to write to all its possible input methods, so this won't conflict with X11.

Example usage of SIGUSR2 (Sway config):

bindsym $mod+o exec pkill -USR2 -n handy

Now, whenever I press alt+o, it'll toggle on, and I press it again, it toggles off. Easy.

(pkill is used here but it doesn't actually "kill" anything. It's just sending that signal to the process matching the name "handy", which we handle!)

Complications

Enabling the wayland feature on enigo seems to affect the overlay monitor detection (only inside of wayland). Just using X11 detection actually works (at least in Sway), but by using the wayland detection, enigo instead early-errors out with:

[2025-10-31T19:06:33Z ERROR enigo::platform::wayland] You tried to get the mouse location. I don't know how this is possible under Wayland. Let me know if there is a new protocol

This seems like an upstream bug which needs to be fixed to properly gracefully fallback.

[cjpais]

Hey thank you so much! How much have you tested this? I don't have a Linux machine currently so I won't be able to test but would love to pull this in

[johnpyp]

So far I've tested with tauri dev only, on Wayland.

I can try a prod build, and verify that it doesn't regress behavior on X11?

[cjpais]

That would be great! And if you do get one could you post it here and also in the discord?

This thread had some stuff for Wayland debug: https://discord.com/channels/1391636091853078608/1432847242766716989

Also if time can you evaluate the impact relative to this PR as well? I want to merge it soon just haven't had time to review the code carefully

#265