Expose staff chat and isolate module resources

[Taahh]

Summary

• add a cancellable StaffChatMessageEvent for toggled and command-based staff chat
• expose staff-chat mode through PlexPlayerView.staffChat()
• allow listeners to replace or cancel a staff-chat message before delivery
• make PlexModule.getResource() prefer resources from the module JAR itself
• route module configuration and migrations through the corrected resource API

Why

Modules currently cannot reliably observe staff chat: toggled staff messages are cancelled internally, direct /adminchat <message> calls emit no chat event, and the public player view does not expose staff-chat mode. This adds supported integration points without requiring modules to depend on Plex server internals.

Module resource loading also delegated to Plex first. A module requesting a common path such as config.yml could therefore receive Plex’s own bundled file. Resource lookup now searches the module URL classloader directly, and the existing migration-specific workaround is consolidated into the public resource method.

The new player-view method has a default implementation to preserve compatibility for third-party PlexPlayerView implementations. Redis-received staff messages intentionally do not fire the local-origin event.

Validation

• ./gradlew :api:javadoc :server:compileJava
• Discord bridge ./gradlew clean build with a bundled config.yml
• git diff --check