refactor(editor): extract WOB/WHM/WOC IO into cli_world_io.cpp

Moves all six world-asset interchange handlers (--export-wob-glb,
--export-wob-obj, --import-wob-obj, --export-whm-glb,
--export-whm-obj, --export-woc-obj) out of main.cpp into a new
cli_world_io.{hpp,cpp} module. WOB / WHM / WOC are our open
replacements for proprietary WMO / ADT-heightmap / ADT-collision
data; these are the bridge that lets the open formats round-trip
through Blender, MeshLab, Three.js, and the rest of the standard
3D toolchain.

main.cpp shrinks by 858 lines (8,997 to 8,140). The single-mesh
--import-obj handler stays inline for now -- it shadow-mirrors
cli_wom_io's --import-stl semantics and will move there next.

tools/editor/cli_world_io.hpp

@@ -0,0 +1,24 @@
+#pragma once
+
+namespace wowee {
+namespace editor {
+namespace cli {
+
+// Dispatch the world-asset interchange handlers. WOB / WHM / WOC
+// are our open replacements for proprietary WMO / ADT-heightmap /
+// ADT-collision data; these handlers bridge them to the formats
+// every other 3D tool understands so the open-format ecosystem
+// is actually usable.
+//   --export-wob-glb    WOB -> glTF 2.0 binary
+//   --export-wob-obj    WOB -> Wavefront OBJ (per-group)
+//   --import-wob-obj    Wavefront OBJ -> WOB (preserves doodads)
+//   --export-whm-glb    WHM/WOT terrain -> glTF 2.0 (per-chunk)
+//   --export-whm-obj    WHM/WOT terrain -> Wavefront OBJ
+//   --export-woc-obj    WOC collision -> OBJ (grouped by walkability)
+//
+// Returns true if matched; outRc holds the exit code.
+bool handleWorldIo(int& i, int argc, char** argv, int& outRc);
+
+} // namespace cli
+} // namespace editor
+} // namespace wowee