Add vanilla JS package (@eigenpal/docx-editor-js)

[jedrazb]

Summary

Add a framework-agnostic vanilla JS package that exposes the editor as a simple class consumers can mount into any DOM element — no React, Vue, or other framework required.

Motivation

The core package (@eigenpal/docx-core) is already fully framework-agnostic: managers, layout pipeline, ProseMirror extensions, and DOCX parsing all work without any framework. The React and Vue packages are orchestration wrappers. A vanilla JS package would:

• Enable usage in non-React/Vue environments (Svelte, Angular, plain HTML, web components, etc.)
• Provide the smallest possible bundle (no framework overhead)
• Serve as the foundation that framework wrappers could optionally build on top of

Proposed API

import { DocxEditor } from '@eigenpal/docx-editor-vanilla';

const editor = new DocxEditor(document.getElementById('editor'), {
  zoom: 1,
  // options...
});

await editor.load(docxBlob);

// Imperative API
editor.focus();
editor.undo();
editor.redo();
const blob = await editor.save();
editor.destroy();

// Events
editor.on('selectionChange', (state) => { ... });
editor.on('contentChange', () => { ... });

Scope

In scope

• Orchestration class that wires existing core managers, layout pipeline, and ProseMirror
• Hidden ProseMirror mount + visible pages rendering via LayoutPainter
• Click/selection handling via layout-bridge
• Transaction listener → repaint loop
• Imperative API: load(), save(), focus(), destroy(), undo(), redo()
• Event emitter for selection/content changes
• Headless toolbar API (expose commands, let consumers build their own UI)

Out of scope (for now)

• Built-in toolbar UI (consumers use the commands API)
• Dialogs (find/replace, insert image, etc.)
• These can be added later as optional add-ons

Implementation Notes

The vanilla package replaces what React does in ~3 files:

React Component	Vanilla Equivalent
DocxEditor.tsx (state wiring)	Orchestration class, wire managers
PagedEditor.tsx (render loop, mouse handlers)	Transaction listener → repaint loop
HiddenProseMirror.tsx (PM mount)	new EditorView(hiddenDiv, {...})

Estimated ~500-800 lines of new code, primarily wiring existing @eigenpal/docx-core APIs together. No new rendering or parsing logic needed.