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/forms/fields/themeselect/themeselect.html.twig

@@ -1,31 +0,0 @@
-{% extends "forms/field.html.twig" %}
-
-{% set options = {} %}
-{% for slug, package in admin.themes %}
-    {% set option = {(slug): package.toArray().name} %}
-    {% set options = options|merge(option) %}
-{% endfor %}
-
-{% block global_attributes %}
-    data-grav-selectize="{{ (field.selectize is defined ? field.selectize : {})|json_encode()|e('html_attr') }}"
-    data-grav-field="select"
-    data-grav-disabled="{{ originalValue is null ? 'true' : 'false' }}"
-    data-grav-default="{{ field.default|json_encode()|e('html_attr') }}"
-{% endblock %}
-
-{% block input %}
-    <div class="form-select-wrapper {{ field.size }}">
-        <select class="{{ field.classes }}" name="{{ (scope ~ field.name)|fieldName ~ (field.multiple ? '[]' : '') }}"
-                {% if field.autofocus in ['on', 'true', 1] %}autofocus="autofocus"{% endif %}
-                {% if field.novalidate in ['on', 'true', 1] %}novalidate="novalidate"{% endif %}
-                {% if field.validate.required in ['on', 'true', 1] %}required="required"{% endif %}
-                {% if field.multiple in ['on', 'true', 1] %}multiple="multiple"{% endif %}
-                {% if field.disabled or isDisabledToggleable %}disabled="disabled"{% endif %}>
-            {% for key, text in options %}
-                <option {% if key == value or text in value %}selected="selected"{% endif %} value="{{ field.multiple ? text : key }}">{{ text }}</option>
-            {% endfor %}
-        </select>
-    </div>
-{% endblock %}
-
-