feat: add EventAutoloader for live event streaming from directories/e…

[Shivansh1205]

Summary

Implements the ability to have Phoenix auto-load new events as they are pushed or published to a directory, as discussed in the issue.

Three source strategies

1. apache-listing (polling)

Fetches an Apache/nginx directory index and parses linked .json/.xml files — directly compatible with the JSROOT file listing format at https://root.cern.ch/js/files/. Tracks seen files so each event is only loaded once.

2. rest-endpoint (polling)

Polls any REST API including AWS Lambda. Accepts { url }, { data }, or { events } response shapes.

3. sse (push)

Connects to a Server-Sent Events stream. Zero polling overhead — server pushes events as they happen.

Usage

// Apache directory (JSROOT-style)
this.autoloaderService.start({
  type: 'apache-listing',
  url: 'https://my-server/events/',
  intervalMs: 5000,
});

// AWS Lambda / REST
this.autoloaderService.start({
  type: 'rest-endpoint',
  url: 'https://lambda-url.amazonaws.com/latest-event',
});

// SSE push
this.autoloaderService.start({ type: 'sse', url: '/api/events/stream' });

// Stop
this.autoloaderService.stop();