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/flex-objects/templates/flex/contacts/object/default.html.twig

@@ -1,15 +0,0 @@
-<div class="entry-details">
-    {% if object.website %}
-        <a href="{{ object.website|e }}"><span class="name">{{ object.last_name|e }}, {{ object.first_name|e }}</span></a>
-    {% else %}
-        <span class="name">{{ object.last_name|e }}, {{ object.first_name|e }}</span>
-    {% endif %}
-    {% if object.email %}
-        <p><a href="mailto:{{ object.email|e }}" class="email">{{ object.email|e }}</a></p>
-    {% endif %}
-</div>
-<div class="entry-extra">
-    {% for tag in object.tags %}
-        <span>{{ tag|e }}</span>
-    {% endfor %}
-</div>