docs: Add known plugin incompatibilities section

- Added Known Issues section documenting WP Prometheus incompatibility
- Updated version badge to 0.4.9

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

README.md

@@ -2,7 +2,7 @@
 
 Stream music over ActivityPub - Build your own music streaming platform for Musicians and Labels.
 
-[![Version](https://img.shields.io/badge/version-0.4.0-blue.svg)](CHANGELOG.md)
+[![Version](https://img.shields.io/badge/version-0.4.9-blue.svg)](CHANGELOG.md)
 [![PHP](https://img.shields.io/badge/PHP-%3E%3D8.3-purple.svg)](https://php.net)
 [![WordPress](https://img.shields.io/badge/WordPress-%3E%3D6.4-blue.svg)](https://wordpress.org)
 [![License](https://img.shields.io/badge/license-GPL--2.0%2B-green.svg)](https://www.gnu.org/licenses/gpl-2.0.html)
@@ -39,6 +39,18 @@ WP FediStream is a WordPress plugin that enables musicians, bands, and labels to
 - [ActivityPub Plugin](https://wordpress.org/plugins/activitypub/) - For Fediverse integration
 - [WooCommerce](https://woocommerce.com/) 10.0+ - For selling music
 
+## Known Issues
+
+### Plugin Incompatibilities
+
+The following plugins are known to cause issues when used together with WP FediStream:
+
+| Plugin        | Issue                                                             | Status              |
+|---------------|-------------------------------------------------------------------|---------------------|
+| WP Prometheus | Memory exhaustion (PHP Fatal error) when viewing FediStream pages | Under investigation |
+
+If you encounter memory issues or PHP fatal errors, try deactivating these plugins temporarily to isolate the problem.
+
 ## License Key
 
 WP FediStream requires a valid license key for frontend functionality (player, shortcodes, ActivityPub). The admin dashboard works without a license, allowing you to configure the plugin before activation.