Fix style inconsistencies in bin/ (#7518)

* Use (( )) for the numeric argument test

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* Drop the quotes on a variable inside [[ ]]

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* Use omarchy-pkg-drop instead of raw pacman -Rns

omarchy-pkg-drop already filters to installed packages, so the
2>/dev/null || true suppression is no longer needed.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* Drop defensive checks around default-set commands

ttfx, imagemagick, and networkmanager are all in the default package
set, so their commands are runtime invariants and should be invoked
directly. Removing the nmcli guard also removes the degraded wifi
fallthrough that only ran when nmcli was missing.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

bin/omarchy-transcode-ascii

@@ -101,11 +101,6 @@ if [[ ! -f $image_path ]]; then
   exit 1
 fi
 
-if omarchy-cmd-missing magick; then
-  echo "ImageMagick is required to convert logo images" >&2
-  exit 1
-fi
-
 if [[ $mode == "braille" ]]; then
   pixel_width=$((width * 2))
   pixel_height=$((height * 4))