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/default/data.txt.twig

@@ -1,21 +0,0 @@
-{%- macro render_field(form, fields, scope) %}
-{%- import _self as self %}
-{%- for index, field in fields %}
-    {%- set show_field = attribute(field, "input@") ?? field.store ?? true %}
-    {%- if field.fields %}
-        {%- set new_scope = field.nest_id ? scope ~ field.name ~ '.' : scope -%}
-        {{- self.render_field(form, field.fields, new_scope) }}
-    {%- else %}
-        {%- if show_field %}
-            {%- set value = form.value(scope ~ (field.name ?? index)) -%}
-            {%- if value -%}
-            {{- field.data_label ? field.data_label|t|e : field.label|t|e }}: {{ string(value is iterable ? value|json_encode : value) ~ "\n" }}
-            {%- endif -%}
-        {%- endif %}
-    {%- endif %}
-{%- endfor %}
-{%- endmacro %}
-{%- import _self as macro %}
-{%- autoescape false %}
-{{- macro.render_field(form, form.fields, '') ~ "\n" }}
-{%- endautoescape %}