docs: Update guides for Quill Editor and ActiveAdmin 4.0.0.beta20

- Replace Tom Select references with Quill Editor
- Update all version references to beta20
- Remove irrelevant guides (Tom Select migration, CKEditor upload system)
- Add Quill Editor specific imports and configurations
- Update package.json dependencies to use Quill instead of Tom Select

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docs/activeadmin-4-asset-setup.md

@@ -1,20 +1,20 @@
 # ActiveAdmin 4 Asset Setup (Tailwind CSS v4)
 
 ## Overview
-This guide documents the current, working setup for ActiveAdmin 4.0.0.beta19 with Tailwind CSS v4 and Tom Select (no jQuery).
+This guide documents the current, working setup for ActiveAdmin 4.0.0.beta20 with Tailwind CSS v4 and Quill Editor.
 
 ## Requirements
-- ActiveAdmin 4.0.0.beta19
+- ActiveAdmin 4.0.0.beta20
 - Tailwind CSS v4 via `tailwindcss-rails` (ships `bin/tailwindcss`)
-- ESBuild (or other JS bundler) for ActiveAdmin JS + Tom Select
+- ESBuild (or other JS bundler) for ActiveAdmin JS + Quill Editor
 
 ## 1. Gemfile
 
 ```ruby
 # ActiveAdmin 4 beta
-gem "activeadmin", "4.0.0.beta19"
+gem "activeadmin", "4.0.0.beta20"
 
-gem "activeadmin-tom_select"
+gem "activeadmin_quill_editor"
 
 # Tailwind CSS v4 (bundled CLI)
 gem "tailwindcss-rails", "~> 4.4.0"
@@ -25,9 +25,8 @@ gem "tailwindcss-rails", "~> 4.4.0"
 ```json
 {
   "dependencies": {
-    "@activeadmin/activeadmin": "^4.0.0-beta19",
-    "tom-select": "^2.4.3",
-    "activeadmin-tom_select": "^4.1.0"
+    "@activeadmin/activeadmin": "^4.0.0-beta20",
+    "quill": "^2.0.3"
   },
   "devDependencies": {
     "esbuild": "^0.27.2"
@@ -48,12 +47,10 @@ gem "tailwindcss-rails", "~> 4.4.0"
 ```javascript
 import "@activeadmin/activeadmin";
 
-import TomSelect from "tom-select";
-window.TomSelect = TomSelect;
+import Quill from "quill";
+window.Quill = Quill;
 
-import { setupAutoInit, initSearchableSelects } from "activeadmin-tom_select";
-window.initSearchableSelects = initSearchableSelects;
-setupAutoInit();
+import "activeadmin_quill_editor";
 ```
 
 ## 4. Tailwind Input (app/assets/stylesheets/active_admin.tailwind.css)
@@ -62,7 +59,8 @@ setupAutoInit();
 @import "tailwindcss";
 @config "../../../tailwind-active_admin.config.mjs";
 
-@import "activeadmin-tom_select/css";
+@import "activeadmin/quill_editor/quill.snow";
+@import "activeadmin/quill_editor_input";
 ```
 
 ## 5. Tailwind Config (tailwind-active_admin.config.mjs)
@@ -80,10 +78,10 @@ export default {
     `${activeAdminPath}/vendor/javascript/flowbite.js`,
     `${activeAdminPath}/plugin.js`,
     `${activeAdminPath}/app/views/**/*.{arb,erb,html,rb}`,
-    "./app/admin/**/*.{arb,erb,html,rb}",
-    "./app/views/active_admin/**/*.{arb,erb,html,rb}",
-    "./app/views/admin/**/*.{arb,erb,html,rb}",
-    "./app/views/layouts/active_admin*.{erb,html}",
+    "./app/admin/**/*.{arb,erb,html,rb}`,
+    "./app/views/active_admin/**/*.{arb,erb,html,rb}`,
+    "./app/views/admin/**/*.{arb,erb,html,rb}`,
+    "./app/views/layouts/active_admin*.{erb,html}`,
     "./app/javascript/**/*.js"
   ],
   darkMode: "selector",
@@ -133,7 +131,7 @@ Rake::Task["db:test:prepare"].enhance(["active_admin:build"]) if Rake::Task.task
 bundle binstubs tailwindcss-ruby --force
 ```
 
-## 8. Upgrade Notes (ActiveAdmin 4.0.0.beta19)
+## 8. Upgrade Notes (ActiveAdmin 4.0.0.beta20)
 
 From ActiveAdmin's upgrade guide:
 - `_site_header.html.erb` container class changed from `sticky` to `fixed`.
@@ -155,15 +153,15 @@ From ActiveAdmin's upgrade guide:
 
 ### ActiveAdmin styles not loading
 - Verify `app/assets/builds/active_admin.css` exists.
-- Check that `active_admin.tailwind.css` imports `activeadmin-tom_select/css`.
+- Check that `active_admin.tailwind.css` imports Quill Editor styles.
 
-### Tom Select not initializing
-- Verify `window.TomSelect` in the console.
-- Ensure `setupAutoInit()` is called.
+### Quill Editor not initializing
+- Verify `window.Quill` in the console.
+- Ensure `activeadmin_quill_editor` is imported.
 
 ## Migration Checklist
 
-- [ ] Update ActiveAdmin to 4.0.0.beta19
+- [ ] Update ActiveAdmin to 4.0.0.beta20
 - [ ] Use Tailwind v4 `@import` + `@config`
 - [ ] Add `tailwindcss-rails` (~> 4.4.0) and binstub
 - [ ] Create `tailwind-active_admin.config.mjs` (ESM)