chore: require Node.js 22 and clean up legacy documentation

Updated minimum Node.js version to 22 to align with modern JavaScript features and improved performance. Removed outdated version 3.x documentation and Lambda Layer references as the package now exclusively uses Docker images for better reliability.

- Require Node.js 22 or higher in engines field
- Remove legacy Lambda Layer documentation
- Update all package manager references to pnpm
- Simplify README by removing deprecated sections

🤖 Generated with [Claude Code](https://claude.ai/code)

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

Author: vladholubiev

package.json

@@ -68,7 +68,7 @@
     "typescript": "5.9.2"
   },
   "engines": {
-    "node": ">=16"
+    "node": ">=22"
   },
   "publishConfig": {
     "access": "public"

readme.md

@@ -5,14 +5,15 @@
 ## Install
 
 ```
-$ yarn add @shelf/aws-lambda-libreoffice
+$ pnpm add @shelf/aws-lambda-libreoffice
 ```
 
 ## Features
 
+- **ESM Module Support**: Native ESM package with full TypeScript support
 - Includes CJK and X11 fonts bundled in the [base Docker image](https://github.com/shelfio/libreoffice-lambda-base-image)!
-- Relies on the latest LibreOffice 7.4 version which is not stripped down from features as a previous layer-based version of this package
-- Requires node.js 16x runtime (x86_64)
+- Relies on the latest LibreOffice 7.6 version which is not stripped down from features
+- Requires Node.js 22 or higher (x86_64)
 
 ## Requirements
 
@@ -24,11 +25,11 @@ See the example at [libreoffice-lambda-base-image](https://github.com/shelfio/li
 Example:
 
 ```Dockerfile
-FROM public.ecr.aws/shelf/lambda-libreoffice-base:7.6-node18-x86_64
+FROM public.ecr.aws/shelf/lambda-libreoffice-base:7.6-node20-x86_64
 
 COPY ./ ${LAMBDA_TASK_ROOT}/
 
-RUN yarn install
+RUN pnpm install
 
 CMD [ "handler.handler" ]
 ```
@@ -40,14 +41,16 @@ CMD [ "handler.handler" ]
 - For larger files support, you can [extend Lambda's /tmp space](https://aws.amazon.com/blogs/aws/aws-lambda-now-supports-up-to-10-gb-ephemeral-storage/) using the `ephemeral-storage` parameter
 - Set environment variable `HOME` to `/tmp`
 
-## Usage (For version 4.x; based on a Lambda Docker Image)
+## Usage (ESM)
 
-Given you have packaged your Lambda function as a Docker image, you can now use this package:
+This package is now a native ESM module. If you're using CommonJS, you'll need to use dynamic imports or update your project to use ESM.
+
+### ESM Usage (Recommended)
 
 ```javascript
-const {convertTo, canBeConvertedToPDF} = require('@shelf/aws-lambda-libreoffice');
+import {convertTo, canBeConvertedToPDF} from '@shelf/aws-lambda-libreoffice';
 
-module.exports.handler = async () => {
+export const handler = async () => {
   // assuming there is a document.docx file inside /tmp dir
   // original file will be deleted afterwards
 
@@ -60,20 +63,11 @@ module.exports.handler = async () => {
 };
 ```
 
-## Usage (For version 3.x; based on a Lambda Layer)
-
-This version requires Node 12.x or higher.
-
-**NOTE:** Since version 2.0.0 npm package no longer ships the 85 MB LibreOffice
-but relies upon [libreoffice-lambda-layer](https://github.com/shelfio/libreoffice-lambda-layer) instead.
-Follow the instructions on how to add a lambda layer in [that repo](https://github.com/shelfio/libreoffice-lambda-layer).
-
-```js
-const {convertTo, canBeConvertedToPDF} = require('@shelf/aws-lambda-libreoffice');
+### CommonJS Usage (via dynamic import)
 
+```javascript
 module.exports.handler = async () => {
-  // assuming there is a document.docx file inside /tmp dir
-  // original file will be deleted afterwards
+  const {convertTo, canBeConvertedToPDF} = await import('@shelf/aws-lambda-libreoffice');
 
   if (!canBeConvertedToPDF('document.docx')) {
     return false;
@@ -83,20 +77,6 @@ module.exports.handler = async () => {
 };
 ```
 
-Or if you want more control:
-
-```js
-const {unpack, defaultArgs} = require('@shelf/aws-lambda-libreoffice');
-
-await unpack(); // default path /tmp/instdir/program/soffice.bin
-
-execSync(
-  `/tmp/instdir/program/soffice.bin ${defaultArgs.join(
-    ' '
-  )} --convert-to pdf file.docx --outdir /tmp`
-);
-```
-
 ## Troubleshooting
 
 - Please allocate at least **3008 MB** of RAM for your Lambda function.
@@ -105,34 +85,46 @@ execSync(
 
 ## See Also
 
-- [libreoffice-lambda-base-image](https://github.com/shelfio/libreoffice-lambda-base-image) - a base Docker image for you Lambdas
-- [libreoffice-lambda-layer](https://github.com/shelfio/libreoffice-lambda-layer) - deprecated, not updated anymore, used the Docker image above
+- [libreoffice-lambda-base-image](https://github.com/shelfio/libreoffice-lambda-base-image) - a base Docker image for your Lambdas
 - [serverless-libreoffice](https://github.com/vladgolubev/serverless-libreoffice) - original implementation
 - [aws-lambda-tesseract](https://github.com/shelfio/aws-lambda-tesseract)
 - [aws-lambda-brotli-unpacker](https://github.com/shelfio/aws-lambda-brotli-unpacker)
 - [chrome-aws-lambda](https://github.com/alixaxel/chrome-aws-lambda)
 
 ## Test
 
-Beside unit tests that could be run via `yarn test`, there are integration tests.
+Beside unit tests that could be run via `pnpm test`, there are integration tests.
 
-Smoke test that it works:
+### Running Tests
 
 ```sh
+# Unit tests
+pnpm test
+
+# Integration test with Docker/Podman
 cd test
 ./test.sh
 
-# copy converted PDF file from container to the host to see if it's ok
-export CID=$(cat ./cid)
-docker cp $CID:/tmp/test.pdf ./test.pdf
+# The test will:
+# 1. Build the ESM code and transpile to CommonJS for Lambda compatibility
+# 2. Process all files in test-data/ directory
+# 3. Generate PDFs in the same test-data/ directory
+# 4. Show conversion summary
 ```
 
+The test setup includes:
+
+- Automatic ESM to CommonJS transpilation using esbuild
+- Batch conversion of multiple file types (DOCX, HTML, etc.)
+- Volume mounting for easy PDF retrieval
+- Sample test files in `test/test-data/`
+
 ## Publish
 
 ```sh
 $ git checkout master
-$ yarn version
-$ yarn publish
+$ pnpm version
+$ pnpm publish
 $ git push origin master --tags
 ```