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/scss/_preset.scss

@@ -1,69 +0,0 @@
-// Flex-Objects
-/* Flex Objects Admin Styles */
-
-#directory {
-
-  .search-wrapper {
-    input, select {
-      color: $form-field-text;
-      border: 1px solid $form-border;
-      background-color: $form-field-bg;
-
-      @include placeholder {
-        @if (lightness($form-field-bg) < 50) {
-          color: darken($form-field-text, 25%);
-        } @else {
-          color: lighten($form-field-text, 25%);
-        }
-      }
-    }
-  }
-
-  .edit-action {
-    color: $button-bg !important;
-  }
-
-  .delete-action {
-    color: $critical-bg !important;
-  }
-
-  thead {
-    tr {
-      background: darken($content-bg,2%);
-    }
-  }
-
-  tbody {
-    tr:nth-child(even) {
-      background: lighten($content-bg,1%);
-    }
-  }
-
-  i.published {
-    color: $flat-green-4;
-  }
-
-  i.unpublished {
-    color: $flat-red-1;
-  }
-
-  .flex-list-pagination {
-    background: darken($content-bg,1%);
-    border-top: 1px solid darken($content-bg,5%);
-
-    .flex-objects-pagination {
-      .button {
-        color: $content-header;
-
-        &.active {
-          color: $button-text;
-          background: $button-bg;
-        }
-
-        &.disabled {
-          color: lighten($content-text, 15%);
-        }
-      }
-    }
-  }
-}