chore: fix what a pass over the tree turned up

- zed asked for Hack Nerd Font, which is not installed; the fonts here are
  UbuntuSans and UbuntuSansMono, so it had been rendering in a fallback.
- /etc/mpv/mpv.conf was deployed for a player that is not installed; vlc is.
- The /etc/stasis/stasis.rune entry is unreachable now that the config is
  seeded into the home directory, which stasis prefers.
- Comments referring to Arch now name moonarch, the repository they actually
  describe.
- The project inputs follow their default branch, not a release tag.

modules/zed.nix

@@ -25,11 +25,11 @@ let
       "base_keymap": "SublimeText",
       "cursor_shape": "block",
       "ui_font_size": 14,
-      "ui_font_family": "Hack Nerd Font",
+      "ui_font_family": "UbuntuSans Nerd Font",
       "ui_font_features": {
         "calt": true
       },
-      "buffer_font_family": "Hack Nerd Font",
+      "buffer_font_family": "UbuntuSansMono Nerd Font",
       "buffer_font_size": 14,
       "theme": {
         "mode": "system",