The handleMsgMhfGetPaperData function was 565 lines, but most of
it was inline data table literals. Extract tower config (case 5)
and tower scaling (case 6) slices into package-level vars in
handlers_data_paper_tables.go, reducing the handler to 73 lines
while co-locating all paper data tables in one file.
Add package-level documentation (doc.go) to all 22 first-party
packages and godoc comments to ~150 previously undocumented
exported symbols across common/, network/, and server/.
