Add schema instructions and update dependencies

Introduces a new documentation file outlining schema requirements for JSON files in the `multiflexi/*.app.json` directory.

Updates multiple composer dependencies to newer versions, improving compatibility and incorporating the latest features and fixes.

Refines `sms_input.multiflexi.app.json` structure to ensure consistency with schema requirements.

Author: Vitexus

.github/copilot-instructions.md

@@ -0,0 +1,3 @@
+# Copilot Instructions
+
+All files in the multiflexi/*.app.json directory must conform to the schema available at: https://raw.githubusercontent.com/VitexSoftware/php-vitexsoftware-multiflexi-core/refs/heads/main/multiflexi.app.schema.json