Refactor from Tailwind CSS to SCSS/Bootstrap

Major changes:
- Replace Tailwind with SCSS using Bootstrap-compatible variables
- Add Gulp build system for SCSS and JS compilation
- Split JS into modular partials (_events, _filters, _preview, etc.)

CSS fixes:
- Fix preview popover visibility (remove conflicting modal.scss rule)
- Fix search input max-width override for parent form styles
- Add filter panel styling (toggle buttons, chips, values row)
- Add group-body padding with negative margins on modifiers
- Style filter-group-toggle with eye icon for preview

JS additions:
- Add showGroupPreviewPopover for group count badge clicks
- Add showItemsPopover for rendering preview popover
- Add renderPreviewItems for product list rendering
- Add eye icon to filter toggle button generation

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

package.json

@@ -1,12 +1,22 @@
 {
-  "name": "prestashop-target-conditions",
-  "version": "1.0.0",
-  "description": "Target conditions widget for PrestaShop modules",
+  "name": "prestashop-entity-selector",
+  "version": "2.0.0",
+  "description": "Universal entity selection widget for PrestaShop admin controllers",
   "scripts": {
-    "build:css": "npx tailwindcss -i ./assets/css/admin/tailwind-input.css -o ./assets/css/admin/tailwind-output.css --minify",
-    "watch:css": "npx tailwindcss -i ./assets/css/admin/tailwind-input.css -o ./assets/css/admin/tailwind-output.css --watch"
+    "build": "gulp build",
+    "build:css": "gulp scss",
+    "build:js": "gulp js",
+    "watch": "gulp watch",
+    "watch:css": "gulp watch:scss",
+    "watch:js": "gulp watch:js"
   },
   "devDependencies": {
-    "tailwindcss": "^3.4.1"
+    "gulp": "^4.0.2",
+    "gulp-concat": "^2.6.1",
+    "gulp-rename": "^2.0.0",
+    "gulp-sass": "^5.1.0",
+    "gulp-sourcemaps": "^3.0.0",
+    "gulp-terser": "^2.1.0",
+    "sass": "^1.63.6"
   }
 }