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/form.html.twig

@@ -1,34 +0,0 @@
-{#
-DO NOT MODIFY!
-
-Default layout can be found in form plugin or your theme:
-
-templates/forms/layouts/form/default-form.html.twig
-templates/forms/layouts/field/default-field.html.twig
-templates/forms/layouts/button/default-button.html.twig
-
-If you want to use multiple different layouts in your site, you can do:
-
-```
-form:
-  name: my-form
-  layout: tailwind
-```
-
-and copy the above files to:
-
-templates/forms/layouts/form/tailwind-form.html.twig
-templates/forms/layouts/field/tailwind-field.html.twig
-templates/forms/layouts/button/tailwind-button.html.twig
-
-You can also override individual fields by copying (using text field as an example):
-
-templates/forms/fields/text/text.html.twig -> templates/forms/fields/text/tailwind-text.html.twig
-
-#}
-{% extends "forms/default/form.html.twig" %}
-
-{% block xhr %}
-{% include 'forms/layouts/xhr.html.twig' %}
-{% endblock %}
-