Address Moodle Marketplace review for mod_meetletacbfree 1.1.3.

Migrate legacy ajax/JS to external services and AMD, enable TLS verification, scope admin CSS with RTLCSS-safe rules, and fix README/lang/boilerplate gaps.

Co-authored-by: Cursor <cursoragent@cursor.com>

templates/participant_form_add.mustache

@@ -1,3 +1,23 @@
+{{!
+    This file is part of Moodle - http://moodle.org/
+
+    Moodle is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    Moodle is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+    @template mod_meetletacbfree/participant_form_add
+    @copyright  2026 MeetLet <info@meetlet.net>
+    @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+}}
 <tr id="participant_list_tr_{{selectiontypevalue}}-{{selectionvalue}}">
     <td class="participant_list_c0"><b><i>{{participanttype}}</i></b></td>
     <td class="participant_list_c1">{{participantvalue}}</td>