fix: use niri include instead of copying system config to user dir

transform.sh was hard-copying /etc/xdg/niri/config.kdl to ~/.config/niri/,
causing the user config to go stale after system updates. Now seeds a minimal
user config with `include "/etc/xdg/niri/config.kdl"` so system defaults
always stay current and users can add overrides below the include.

scripts/transform.sh

@@ -303,12 +303,29 @@ for src_dir in /etc/xdg/*/; do
     [[ "$app_name" == "gtk-4.0" ]] && continue
     # kanshi profiles are user-specific (display setup) — only seed, never overwrite
     [[ "$app_name" == "kanshi" ]] && [[ -d "$HOME/.config/kanshi" ]] && continue
+    # niri user config includes system config — never overwrite (handled below)
+    [[ "$app_name" == "niri" ]] && continue
     dest_dir="$HOME/.config/$app_name"
     rm -rf "$dest_dir" 2>/dev/null || sudo rm -rf "$dest_dir"
     cp -r --no-preserve=ownership "$src_dir" "$dest_dir"
     log "  + $app_name/"
 done
 
+# Niri: seed user config with include of system config (preserves user overrides)
+niri_user_config="$HOME/.config/niri/config.kdl"
+if [[ ! -f "$niri_user_config" ]]; then
+    mkdir -p "$HOME/.config/niri"
+    cat > "$niri_user_config" << 'NIRI_EOF'
+// ABOUTME: Moonarch user niri config — includes system defaults.
+// ABOUTME: Add personal overrides below the include statement.
+
+include "/etc/xdg/niri/config.kdl"
+NIRI_EOF
+    log "  + niri/ (seeded with include)"
+else
+    log "  ~ niri/ (user config exists, skipped)"
+fi
+
 # Overwrite configs owned by other packages with moonarch versions
 log "Deploying moonarch config overrides..."
 cp /usr/share/moonarch/walker-config.toml "$HOME/.config/walker/config.toml"