refactor(dotfiles): rename system/ to common/ and remove unused configs

Rename dotfiles/system to dotfiles/common for clarity - indicates
shared dotfiles used across all desktop environments (DWM, Hyprland).

Removed config directories for uninstalled applications:
- ghostty (using different terminal)
- lf (using ranger instead)
- mopidy (using mpd instead)
- nitrogen (X11-only, obsolete for Wayland)
- pychess (not installed)
- JetBrains (not installed via archsetup)
- youtube-dl (using yt-dlp with different config location)

Kept audacious config for potential future use.

Updated all references in archsetup, CLAUDE.md, todo.org, and
validation.sh.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

1 files changed, 0 insertions, 0 deletions

diff --git a/dotfiles/common/pictures/wallpaper/nasa-earth-day.jpg b/dotfiles/common/pictures/wallpaper/nasa-earth-day.jpg
new file mode 100644
index 0000000..25098f1
--- /dev/null
+++ b/dotfiles/common/pictures/wallpaper/nasa-earth-day.jpg