feat: v0.2.1 — reference links, context menu, RTL, ja/ko, regex search, hooks, copy API

## Added
- Reference link/image resolution: [text][ref] + ![alt][ref] with [ref]: url definitions
- Right-click context menu: undo/redo/cut/copy/paste/selectAll + custom items
- RTL CSS layout support for Arabic, Hebrew, Persian etc.
- Japanese (ja) and Korean (ko) locales with 60+ keys each
- Divider position localStorage persistence
- Regex search toggle in search/replace panel
- Export HTML with embedded CSS styles
- beforeChange / afterChange lifecycle hooks (instance + global)
- copyAsMarkdown() / copyAsHTML() clipboard APIs
- CHANGELOG.md, CONTRIBUTING.md, CI workflow (.github/workflows/ci.yml)
- 2 new test suites: index.test.ts, styles.test.ts (684 total tests, +74)

## Changed
- autoSave plugin: closure-based state per instance instead of this context
- Plugin install() now receives options as second argument
- RTL locale detection: now uses language prefix (ar-SA → RTL)
- Rollup dev mode: only builds UMD format
- prepublishOnly now includes typecheck + test
- Version bumped to 0.2.1

## Fixed
- [text][ref] now correctly renders as link (was raw text)
- ![alt][ref] no longer produces empty src
- autoSave plugin state isolation across multiple editor instances
- Footnote definitions no longer consumed by refDef handler

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@metona-team/metona-editor",
-  "version": "0.2.0",
+  "version": "0.2.1",
   "description": "Type-safe, lightweight, zero-dependency Markdown Editor. Desktop-first. React-free. Single-file bundle.",
   "type": "module",
   "main": "dist/metona-editor.js",
@@ -30,7 +30,7 @@
     "lint:fix": "eslint src/ --fix",
     "format": "prettier --write src/",
     "typecheck": "tsc --noEmit",
-    "prepublishOnly": "npm run build"
+    "prepublishOnly": "npm run typecheck && npm test && npm run build"
   },
   "repository": {
     "type": "git",