Moves three derived-data maintenance handlers (--fix-zone,
--regen-collision, --build-woc) out of main.cpp into a new
cli_zone_data.{hpp,cpp} module. Distinct from cli_repair
(which fixes manifest-vs-disk drift): these rebuild derived
terrain data and clean up JSON files via load+save:
- fix-zone re-parses + re-saves every JSON sidecar to apply
load-time scrubs and save-time caps
- regen-collision rebuilds WOC for every WHM/WOT in a zone
- build-woc handles single-tile WOC generation
main.cpp shrinks by 104 lines (1,541 to 1,437).
