docs: map existing codebase with PAUL

- stack.md - PrestaShop 1.7.x, PHP, Smarty, SCSS, modules
- architecture.md - MVC + hooks, override mechanism, CQRS in src/
- structure.md - Directory layout, key file locations
- conventions.md - PHP/Smarty/SCSS/JS conventions, PS patterns
- testing.md - No automated tests in custom modules
- integrations.md - Allegro, Empik, BaseLinker, shipping, payments
- concerns.md - Override fragility, EOL risk, missing CI/CD
- db_schema.md - Custom tables, modified core tables

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

.paul/codebase/todo.md

@@ -0,0 +1,4 @@
+# TODO
+
+> Luźny parking pomysłów, rzeczy do sprawdzenia, rzeczy które mogą nigdy nie być wdrożone.
+> Nie wymaga formalności — wrzucaj co chcesz.