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/app/fields/tabs.js

@@ -1,14 +0,0 @@
-import $ from 'jquery';
-
-$('body').on('touchstart click', '[data-tabid]', (event) => {
-    event && event.stopPropagation();
-    let target = $(event.currentTarget);
-
-    const panel = $(`[id="${target.data('tabid')}"]`);
-
-    target.siblings('[data-tabid]').removeClass('active');
-    target.addClass('active');
-
-    panel.siblings('[id]').removeClass('active');
-    panel.addClass('active');
-});