feat(computer-use): package computer-use-linux and cua-driver

Package the prebuilt releases (computer-use-linux v0.7.1 and
cua-driver-rs v0.24.0) under pkgs/, injected through thin callPackage
overlays so they are easy to relocate to the NUR repository later.

overlays/computer-use-linux.nix

@@ -0,0 +1,3 @@
+_: _final: prev: {
+  computer-use-linux = prev.callPackage ../pkgs/computer-use-linux { };
+}

overlays/cua-driver.nix

@@ -0,0 +1,3 @@
+_: _final: prev: {
+  cua-driver = prev.callPackage ../pkgs/cua-driver { };
+}