feat: derive desktop input and SDDM scale from host metadata

modules/features/niri/default.nix

@@ -23,6 +23,8 @@
       ...
     }:
     let
+      hostInput = config.meta.host.input;
+
       outputs = lib.mapAttrs (
         _: display:
         {
@@ -49,6 +51,27 @@
           rawTerminalAttrPath;
       terminalPackage = lib.attrByPath terminalAttrPath null pkgs;
       hasMainProgram = terminalPackage != null && terminalPackage ? meta.mainProgram;
+
+      mouseSettings = lib.filterAttrs (_: value: value != null) {
+        accel-profile = hostInput.mouse.accelProfile;
+        accel-speed = hostInput.mouse.accelSpeed;
+        left-handed = hostInput.mouse.leftHanded;
+        middle-emulation = hostInput.mouse.middleEmulation;
+        natural-scroll = hostInput.mouse.naturalScrolling;
+        scroll-method = hostInput.mouse.scrollMethod;
+      };
+
+      touchpadSettings = lib.filterAttrs (_: value: value != null) {
+        accel-profile = hostInput.touchpad.accelProfile;
+        accel-speed = hostInput.touchpad.accelSpeed;
+        click-method = hostInput.touchpad.clickMethod;
+        dwt = hostInput.touchpad.disableWhileTyping;
+        left-handed = hostInput.touchpad.leftHanded;
+        middle-emulation = hostInput.touchpad.middleEmulation;
+        natural-scroll = hostInput.touchpad.naturalScrolling;
+        scroll-method = hostInput.touchpad.scrollMethod;
+        tap = hostInput.touchpad.tapping;
+      };
     in
     {
       assertions = [
@@ -139,7 +162,12 @@
             repeat-rate = 50;
             xkb.options = "caps:escape";
           };
-          mouse.accel-speed = 0.4;
+        }
+        // lib.optionalAttrs (mouseSettings != { }) {
+          mouse = mouseSettings;
+        }
+        // lib.optionalAttrs (touchpadSettings != { }) {
+          touchpad = touchpadSettings;
         };
 
         binds =