chore: add spec-kit and standardize signatures

- Added GitHub spec-kit for development workflow
- Standardized file signatures to Descomplicar® format
- Updated development configuration

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

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

tests/TestCase.php

@@ -1,3 +1,8 @@
+/**
+ * Descomplicar® Crescimento Digital
+ * https://descomplicar.pt
+ */
+
 <?php
 
 /**