nix-darwin's karabiner module is broken with 15.7+ - the karabiner_grabber
and karabiner_observer binaries no longer exist, causing system daemons to
fail with exit code 78. Moved karabiner-elements to homebrew cask which
handles its own service registration correctly.
Also adds macfuse cask and gromgit/fuse/sshfs-mac brew, updates
agentcomputer-cli flake input, and tweaks zsh alias.
