fix(structure): Correct case-sensitivity for Linux compatibility

Rename folders to match PHP PSR-4 autoloading conventions:
- schemas → Schemas
- shared → Shared
- Wordpress → WordPress (in all locations)

Fixes deployment issues on Linux servers where filesystem is case-sensitive.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

Shared/Domain/Contracts/TransactionManagerInterface.php

@@ -0,0 +1,11 @@
+<?php
+declare(strict_types=1);
+
+namespace ROITheme\Shared\Domain\Contracts;
+
+/**
+ * Interface para gestión de transacciones de base de datos
+ */
+interface TransactionManagerInterface {
+    // Se implementará completamente en Fase 5
+}