feat(editor): add --audit-watertight-wob building QA tool

Sibling of --audit-watertight that walks every .wob under
<root> and runs the welded watertight check on every group.
A WOB passes only if every group is closed — interior rooms
in a real building should each be a closed solid even
though the building as a whole has intentional portal
openings between them.

Per-failure detail lists which groups failed and why
(boundary edge count + non-manifold edge count). Exit code
is the number of failed buildings (capped at 255) — same
CI-friendly contract as the WOM audit.

Smoke tested against /tmp/migtest cube.wob: PASS, 12 tris,
exit code 0.

tools/editor/cli_arg_required.cpp

@@ -142,7 +142,7 @@ const char* const kArgRequired[] = {
     "--bake-zone-glb", "--bake-zone-stl", "--bake-zone-obj",
     "--bake-project-obj", "--bake-project-stl", "--bake-project-glb",
     "--bake-wom-collision", "--bake-wob-collision",
-    "--audit-watertight",
+    "--audit-watertight", "--audit-watertight-wob",
     "--convert-m2", "--convert-m2-batch",
     "--convert-wmo", "--convert-wmo-batch",
     "--convert-dbc-json", "--convert-dbc-batch", "--convert-json-dbc",