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/admin/themes/grav/templates/partials/blueprints-new-folder.html.twig

@@ -1,18 +0,0 @@
-{% set form_id = form_id ? form_id : 'blueprints' %}
-{% set scope = scope ?: 'data.' %}
-{% set field_layout = 'admin' %}
-
-<form {% if form_action %}action="{{ form_action }}"{% endif %} id="{{ form_id }}" method="post" data-grav-form="{{ form_id }}" data-grav-keepalive="true">
-    {% embed 'forms/default/fields.html.twig' with {name: null, fields: blueprints.fields} %}
-        {% block inner_markup_field_open %}<div class="block block-{{ field.type }}">{% endblock %}
-        {% block inner_markup_field_close %}</div>{% endblock %}
-    {% endembed %}
-
-    <input type="hidden" name="task" value="saveNewFolder" />
-    <div class="button-bar">
-        <button class="button primary">{{ "PLUGIN_ADMIN.SAVE"|t }}</button>
-    </div>
-
-    {{ nonce_field('admin-form', 'admin-nonce')|raw }}
-
-</form>