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.

.chezmoiscripts/run_onchange_after_20-gh-extensions.sh.tmpl

@@ -0,0 +1,25 @@
+#!/usr/bin/env fish
+# Install gh extensions declared in .chezmoidata/packages.yaml.
+# A fish script, so fish's config (~/.config/fish, applied before after-scripts
+# run) is sourced first: PATH (mise, ~/.local/bin, ~/.cargo/bin) and
+# GITHUB_TOKEN (conf.d/10-env.fish) match a fish session.
+# gh_extensions hash: {{ .packages.shared.gh_extensions | toJson | sha256sum }}
+
+if not command -q gh
+    echo "warning: gh not installed — skipping extensions" >&2
+    exit 0
+end
+if not gh auth status >/dev/null 2>&1
+    echo "warning: gh not authenticated — run 'gh auth login', then 'chezmoi apply' again" >&2
+    exit 0
+end
+
+set -l installed (gh extension list 2>/dev/null | string split -f2 \t)
+set -l failed
+for ext in{{ range .packages.shared.gh_extensions }} {{ . | quote }}{{ end }}
+    contains -- $ext $installed; or gh extension install $ext; or set -a failed $ext
+end
+if set -q failed[1]
+    echo "error: gh extension install failed for: $failed" >&2
+    exit 1
+end