Move plugins to manifest, pin Docker version, add Makefile

- Add plugins.txt listing all plugins for reproducible installs
- Add Makefile with setup/start/stop/install-plugins targets
- Remove user/plugins/ from git tracking
- Pin Docker image to 1.7.49.5-ls244

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

plugins/form/templates/forms/fields/captcha/captcha.html.twig

@@ -1,18 +0,0 @@
-{% extends "forms/field.html.twig" %}
-
-{% block field %}
-    {# This main captcha field serves as a router to the appropriate provider template #}
-    {% set provider = field.provider %}
-
-    {% if provider is not defined or provider == null %}
-        {% set provider = 'recaptcha' %}
-    {% endif %}
-
-    {% set template = 'forms/fields/' ~ provider ~ '/' ~ provider ~ '.html.twig' %}
-
-    {% if captcha_template_exists(template) %}
-        {% include template with {'field': field} %}
-    {% else %}
-      <div class="form-error" style="color:#c00000;">ERROR - unknown captcha provider: <strong>{{ provider }}</strong></div>
-    {% endif %}
-{% endblock %}