Face-tagged 3MF exchange: format spec, reader, geometry.import.mesh

docs/formats/tagged-mesh.md defines the exchange: 3MF Core with an optional
ft:face attribute per triangle (and ft:faces per object) in a ModelCraft
namespace. modelcraft_geometry::tagged_mesh::read_3mf reads it from bytes
(wasm), capping every size and count and range-checking every index and
coordinate. geometry.import.mesh adds the surfaces to the session, which keeps
them beside the open design and restores them when a command fails.

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

Cargo.lock

@@ -459,17 +459,20 @@ dependencies = [
  "serde",
  "serde_json",
  "thiserror 2.0.21",
+ "zip",
 ]
 
 [[package]]
 name = "modelcraft-geometry"
 version = "0.1.0"
 dependencies = [
+ "quick-xml",
  "solidcraft-doc",
  "solidcraft-geom",
  "solidcraft-io",
  "solidcraft-kernel",
  "thiserror 2.0.21",
+ "zip",
 ]
 
 [[package]]