extension "wolrd copy" function for "Custom worlds" folder

### Enhancement Type

Improve an existing feature

### Describe the enhancement

Hello,
you have the feature that a worldfolder is copied at startup. (environment variable "WORLD" and "FORCE_WORLD_COPY") I wanted to ask if it is possible that this also works for a "Custom worlds directory path". So that at startup all worlds from a folder are copied into the "Custom worlds" folder.

best regards

EvilBlood92

Start by tracing the startup handling for the WORLD and FORCE_WORLD_COPY environment variables, then compare it with the configured Custom worlds directory path. Verify that startup copies all worlds from the requested source folder into the Custom worlds folder without changing existing behavior for a single worldfolder. There are no files or tests named in the issue, so identify the relevant startup entry point and add coverage if the project’s existing tests support it.

Written by the indexing model from the issue text.