Bundle CHIM-Custom server package for automatic install

[RANGROO]

Summary

• generate a server-only schema-v4 .dwpkg
• place it at SkyrimPlugin/package/CHIM/server-plugins/CHIM-Custom/<version>.dwpkg
• let CHIM transfer and install the server component automatically when a save loads
• remove the launcher/game-payload broker fields from the package manifest

Validation

• package builder completed successfully
• archive contents and manifest were inspected
• the generated package installed through the live chunk API
• both CHIM-Custom migrations completed

Dependencies

• Dwemer-Dynamics/CHIM automatic server sync PR
• Install bundled server plugins automatically from CHIM abeiro/HerikaServer#591