mesh.hex.blocks: one conforming hex mesh of a design split into blocks

Meshes the open design's bodies (or the listed ones) as the cells of one
conforming all-hex mesh with one size and tessellation tolerance for all;
elements carry their cell's body, boundary faces its B-rep faces. A cell
that is no block, or cells that touch without sharing whole faces, is an
error naming the bodies. Catalogue entry with its VectorCraft icon, the
MCP mesh tool's hex_blocks method, docs/features.md.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm

crates/engine/src/catalogue.rs

@@ -272,6 +272,13 @@ pub static CATALOGUE: &[Capability] = &[
         "Hex mesh swept along extrusions (several levels), around revolutions, or from a source face to a target",
         &["mesh.hex.generate"],
     ),
+    ready(
+        "mesh.hex.blocks",
+        "Block Hex",
+        Mesh,
+        "Structured Hex",
+        "One conforming hex mesh of a part split into six-sided blocks: shared faces meshed once",
+    ),
     soon("mesh.hex.decompose", "Decompose", Mesh, "Structured Hex", "M5", "Find sweepable and mappable regions and propose the splits"),
     soon("mesh.transition", "Transition", Mesh, "Structured Hex", "M5", "Conforming tet–hex interfaces with pyramids"),
     soon("mesh.hex.octree", "All-Hex", Mesh, "Automatic Hex", "M6", "Octree dual all-hex mesh of any part"),