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/scss/configuration/template/_base.scss

@@ -1,5 +0,0 @@
-// Colors
-@import "colors";
-
-// Variables
-@import "variables";

plugins/admin/themes/grav/scss/configuration/template/_colors.scss

@@ -1,15 +0,0 @@
-// Core
-$white:							#ffffff;
-$black:							#000000;
-$light-gray:					#dddddd;
-
-$core-border-color:				$light-gray;
-$core-border-color-hover: 		darken($core-border-color, 10);
-
-$code-text:						#c7254e;
-$code-bg:						#f9f2f4;
-$pre-text:						#237794;
-$pre-bg:						#f6f6f6;
-
-// Shadows
-$core-box-shadow: 				inset 0 1px 3px hsla(0, 0%, 0%, 0.06);

plugins/admin/themes/grav/scss/configuration/template/_variables.scss

@@ -1,22 +0,0 @@
-// Sizes
-$header-height: 5rem;
-$footer-height: 6rem;
-$border-radius: 4px;
-
-// Font Weights
-$font-weight-bold: 600;
-$font-weight-regular: 400;
-$font-weight-light:300;
-
-// Global Paddings
-$padding-default: 1.5rem;
-$padding-horiz: 7rem;
-$padding-vert: 3rem;
-
-//Forms
-$form-label-width: 30%;
-$form-border-radius: 4px;
-$form-border-width: 1px;
-$form-label-pad: 5px 0 5px 3rem;
-$form-input-pad: 5px 10px;
-$form-select-pad: 5px 30px 5px 10px;