Initial import: chezmoi source for CachyOS + Umbriel + Noctalia

Imported from prdlk/dotfiles master (efdd827). Drops the niri, Hyprland/Omarchy,
macOS, and Blume docs-site layers; docs/ is plain Markdown.

dot_local/bin/executable_gdc

@@ -0,0 +1,9 @@
+#!/bin/sh
+# Discard all git changes with gum confirmation.
+if gum confirm "Discard all uncommitted changes? This is irreversible."; then
+    git reset --hard HEAD
+    git clean -fd
+    echo "Changes wiped."
+else
+    echo "Operation aborted."
+fi