feat(editor): add --gen-mesh-table furniture primitive

40th procedural mesh: simple 5-box table — flat top slab on
4 vertical corner legs. Pairs with --gen-mesh-bench /
--gen-mesh-throne / --gen-mesh-bookshelf for taverns,
dining halls, libraries, and study set dressing.

Defaults to 1.6 × 1.0 base × 0.85 tall, 0.10-square legs,
0.06-thick top — sensible dining-table proportions.
Customizable per dimension so a single primitive covers
desks, end tables, and big banquet tables.

tools/editor/main.cpp

@@ -130,6 +130,7 @@ int main(int argc, char* argv[]) {
         "--gen-mesh-banner", "--gen-mesh-grave", "--gen-mesh-bench",
         "--gen-mesh-shrine", "--gen-mesh-totem", "--gen-mesh-cage",
         "--gen-mesh-throne", "--gen-mesh-coffin", "--gen-mesh-bookshelf",
+        "--gen-mesh-table",
         "--gen-texture-gradient",
         "--gen-mesh-from-heightmap", "--export-mesh-heightmap",
         "--displace-mesh",