Add organization management functionality and logo image

- Implemented organization creation, editing, and activity management in orgs.php.
- Added safe path segment function to sanitize input.
- Included file upload handling for activity photos.
- Created a new logo image for the application.

public_html/entreaulas/index.php

@@ -1,11 +1,4 @@
 <?php
 ini_set("display_errors", 0);
-$PAGE_TITLE = "EntreAulas - Inicio";
-require_once "_incl/pre-body.php"; ?>
-<div class="card pad">
-    <h2>Recursos:</h2>
-    <ul>
-        <li><a class="btn btn-secondary" href="/entreaulas/recursos/letras-a4.php">Generador de Letras A4 con varios estilos para imprimir</a></li>
-    </ul>
-</div>
-<?php require_once "_incl/post-body.php"; ?>
+header('Location: /aulatek/');
+exit;