Fix module-owned resource lookup

[Taahh]

Summary

• make PlexModule.getResource() search the requesting module JAR before Plex’s parent classloader
• route module configuration defaults through the corrected resource API
• consolidate the migration loader’s existing child-first workaround into PlexModule.getResource()

Why

Plex module classloaders delegate to Plex first. When a module requests a common resource such as config.yml, the lookup can return Plex’s own bundled configuration instead of the file inside the module JAR. This prevents modules from safely using conventional resource names.

Impact

Modules can bundle and load a normal config.yml without colliding with Plex resources. Existing module migration behavior remains child-first, now through the shared public API.

Validation

• ./gradlew :api:javadoc :server:compileJava
• Discord bridge ./gradlew clean build with config.yml packaged in its JAR
• git diff --check