docs: flip lockscreen references to hyprlock

Replace all gtklock mentions in README, ARCHITECTURE, CLAUDE.md with
hyprlock, and drop the stale gtklock consumer note from theme/colors.css
header comment (hyprlock uses Hyprlang, not CSS imports).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

CLAUDE.md

@@ -76,7 +76,7 @@ dotfiles/
 │   ├── starship/
 │   ├── wofi/
 │   ├── mako/
-│   ├── gtklock/
+│   ├── hyprlock/
 │   └── ...
 ├── install.sh
 ├── packages.txt