fix: obfuscate email in contact links, raise rate limits, make Libre toggleable

- about.php: use EmailObfuscator::email() for contact email link text instead of htmlspecialchars
- SearchController: raise rate limit from 30 to 300 req/min
- request-access.php: raise rate limit from 3 to 30 req/10min
- partage/index.php: raise rate limit from 5 to 50 req/10min
- contenus.php: make Libre option toggleable (remove disabled class), move to top of Degré d'ouverture, remove temporary note about next academic year

app/templates/public/about.php

@@ -83,7 +83,7 @@ function renderEntries(array $entries): string
                             fn($e) => !empty($e),
                         );
                         foreach ($emails as $email): ?>
-                        <a href="<?= EmailObfuscator::mailto($email) ?>"><?= htmlspecialchars($email) ?></a>
+                        <a href="<?= EmailObfuscator::mailto($email) ?>"><?= EmailObfuscator::email($email) ?></a>
                         <?php endforeach;
                         ?>
                     </address>