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, 47 insertions, 0 deletions

diff --git a/dotfiles/common/.zshrc.d/arch-downgrade.sh b/dotfiles/common/.zshrc.d/arch-downgrade.sh
new file mode 100644
index 0000000..f1d01a7
--- /dev/null
+++ b/dotfiles/common/.zshrc.d/arch-downgrade.sh
@@ -0,0 +1,47 @@
+# arch-downgrade.sh
+# Craig Jennings <c@cjennings.net>
+# Downgrade Arch packages with fzf (zsh only)
+
+# Config:
+#   export DG_HELPER=pacman   # or yay, paru, etc.
+#   export DG_FZF_OPTS="..."  # optional extra fzf flags
+
+dg() {
+    emulate -L zsh
+    set -u
+    set -o pipefail
+
+    local helper="${DG_HELPER:-pacman}"
+
+    # Check dependencies
+    for cmd in "$helper" fzf sudo downgrade awk sort; do
+        if ! command -v "${cmd%% *}" >/dev/null 2>&1; then
+            print -u2 -- "Missing dependency: $cmd"
+            return 1
+        fi
+    done
+
+    # List explicitly installed packages
+    local selection
+    selection="$(
+        "$helper" -Qe 2>/dev/null \
+          | fzf --no-multi \
+                --prompt="Pick package to downgrade > " \
+                --height=80% \
+                --reverse \
+                --delimiter=' ' \
+                --preview-window=right:60%:wrap \
+                --preview "$helper -Qi {1} 2>/dev/null || $helper -Si {1}" \
+                ${DG_FZF_OPTS:-}
+    )"
+
+    [[ $? -ne 0 || -z "$selection" ]] && return 0
+
+    local pkg
+    pkg="$(print -r -- "$selection" | head -n1 | awk '{print $1}')"
+
+    if ! sudo downgrade "$pkg"; then
+        print -u2 -- "Downgrade failed for $pkg"
+        return 1
+    fi
+}