Mirrors the --list-project-meshes-detail rename from 976549fe.
After the c0f2ab75 inventory extraction, the older per-mesh
sorted-by-tris listing was shadowed by the per-zone aggregate
that now lives in cli_zone_inventory.cpp.
Renames the older handler to --list-zone-meshes-detail (and
updates its help text + kArgRequired entry) so both views
coexist:
--list-zone-meshes — per-zone aggregate (extracted)
--list-zone-meshes-detail — sorted-by-tris listing
Removes the last duplicate-flag dead code from main.cpp.
155bb1619c