refactor: Remove jQuery dependency and consolidate JavaScript assets

- Rename vendor JS file to activeadmin/quill_editor.js to avoid conflicts
- Update import alias to use 'activeadmin/quill_editor' for consistency
- Remove jQuery-dependent legacy file (quill_editor_input.js)
- Simplify engine asset configuration - only one JS file now
- Update documentation with correct paths and import names
- All functionality preserved with vanilla JavaScript

BREAKING CHANGE: Drops support for jQuery-based initialization.
Applications using the legacy jQuery initialization will need to
update to the new module-based approach.

🤖 Generated with Claude Code

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

app/assets/javascripts/activeadmin/quill_editor_input.js

@@ -1,123 +0,0 @@
-/* globals $ Quill ImageUploader */
-(function () {
-  'use strict';
-
-  // --- functions ---------------------------------------------------------------
-  const initQuillEditors = () => {
-    const defaultTheme = 'snow';
-    const defaultToolbar = [
-      ['bold', 'italic', 'underline'],
-      ['link', 'blockquote', 'code-block'],
-      [{ 'script': 'sub' }, { 'script': 'super' }],
-      [{ 'align': [] }, { list: 'ordered' }, { list: 'bullet' }],
-      [{ 'color': [] }, { 'background': [] }],
-      ['image'],
-      ['clean'],
-    ];
-    const editors = document.querySelectorAll('[data-aa-quill-editor]');
-    const registeredPlugins = {};
-
-    for (let i = 0; i < editors.length; i++) {
-      const content = editors[i].querySelector('[data-aa-quill-content]');
-      const isActive = editors[i].classList.contains('quill-editor--active');
-
-      if (content && !isActive) {
-        // Setup editor options
-        const options = editors[i].getAttribute('data-options') ? JSON.parse(editors[i].getAttribute('data-options')) : {};
-
-        if (!options.theme) options.theme = defaultTheme;
-        if (!options.modules) options.modules = {};
-        if (!options.modules.toolbar) options.modules.toolbar = defaultToolbar;
-
-        // Setup plugin options
-        const pluginOptions = editors[i].getAttribute('data-plugins') ? JSON.parse(editors[i].getAttribute('data-plugins')) : {};
-
-        if (pluginOptions.image_uploader && pluginOptions.image_uploader.server_url) {
-          if (!registeredPlugins.image_uploader) {
-            Quill.register('modules/imageUploader', ImageUploader);
-            registeredPlugins.image_uploader = true;
-          }
-          const opts = pluginOptions.image_uploader;
-
-          options.modules.imageUploader = setupImageUploader(opts.server_url, opts.field_name);
-        }
-
-        // Init editor
-        editors[i]['_quill-editor'] = new Quill(content, options);
-        editors[i].classList += ' quill-editor--active';
-      }
-    }
-
-    const formtastic = document.querySelector('form.formtastic');
-
-    if (formtastic) {
-      formtastic.onsubmit = () => {
-        for (let i = 0; i < editors.length; i++) {
-          const input = editors[i].querySelector('input[type="hidden"]');
-
-          if (editors[i]['_quill-editor'].editor.isBlank()) {
-            input.value = '';
-          } else {
-            input.value = editors[i]['_quill-editor'].root.innerHTML;
-          }
-        }
-      };
-    }
-  };
-
-  const setupImageUploader = (server_url, field_name) => {
-    return {
-      upload: (file) => {
-        return new Promise((resolve, reject) => {
-          const formData = new FormData();
-
-          formData.append(field_name || 'file_upload', file);
-          fetch(server_url, {
-            body: formData,
-            headers: {
-              'X-CSRF-Token': document.querySelector('meta[name="csrf-token"]').getAttribute('content')
-            },
-            method: 'POST'
-          }).then(response => response.json())
-            .then(result => {
-              if (!result.url) {
-                reject('Upload failed');
-              }
-              resolve(result.url);
-            })
-            .catch(error => {
-              reject('Upload failed');
-              console.error('Error: ', error);
-            })
-        })
-      }
-    }
-  }
-
-  // --- public functions --------------------------------------------------------
-  window.getQuillEditors = function() {
-    const editors = document.querySelectorAll('[data-aa-quill-editor]');
-    const list = [];
-
-    editors.forEach(function(editor) { list.push(editor['_quill-editor']) });
-
-    return list;
-  }
-
-  window.getQuillEditorByIndex = function(index) {
-    const editors = document.querySelectorAll('[data-aa-quill-editor]');
-
-    return (index >= 0 && index < editors.length) ? editors[index]['_quill-editor'] : null;
-  }
-
-  window.getQuillEditorByElementId = function(id) {
-    const editor = document.querySelector(`[data-aa-quill-editor]#${id}`);
-
-    return editor ? editor['_quill-editor'] : null;
-  }
-
-  // --- events ------------------------------------------------------------------
-  $(document).ready(initQuillEditors);
-  $(document).on('has_many_add:after', '.has_many_container', initQuillEditors);
-  $(document).on('turbolinks:load', initQuillEditors);
-})();