Add metacircular control programs to rift, orion, and vade

Install mciasctl, mciasgrpcctl, mcrctl, and mcproxyctl via new
configs/mcpkg.nix module. Adds flake inputs for mcias, mcr, and
mc-proxy from git.wntrmute.dev.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

hw/orion/default.nix

@@ -4,5 +4,6 @@
     ./hardware-configuration.nix
     ../../configs/desktop.nix
     ../../configs/qemu.nix
+    ../../configs/mcpkg.nix
   ];
 }