Default both build scripts to orcacad-deps, not the other fork's image

Both scripts defaulted IMAGE to snaporca-deps. That image is Snapmaker-based
and lacks Eigen 5.0.1, CGAL 5.6.3, wx 3.3.2 and Python 3.12 Development.Embed,
so running either script here without an explicit IMAGE= dies at CMake
configure — which is a large part of why this fork reached M8 having never once
compiled (1633005bba). The volume defaults were fixed in that commit; the image
default was missed in both files.

docker-iter-build.sh also never mounted deps_src, so it could not have
configured even with the right image: root CMakeLists.txt:947 FATAL_ERRORs
when deps_src/pybind11/include/pybind11/pybind11.h is absent, and
src/CMakeLists.txt pulls semver/hints/imgui/imguizmo/hidapi from the same tree.
kernel-test.sh got that mount in 1633005bba; this is the same fix for the GUI
build path, needed before the Phase B GUI work can be ported here.

CadDocument.hpp: mate_kind comment, mirrored verbatim from snaporca dbaa104f62
so the header stays byte-identical across forks.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

scripts/docker-iter-build.sh

@@ -1,5 +1,5 @@
 #!/usr/bin/env bash
-# Incremental slicer build against the snaporca-deps base image.
+# Incremental slicer build against the orcacad-deps base image.
 #
 # The deps-baked image (built from scripts/Dockerfile.deps) carries the pinned
 # dependencies at /OrcaSlicer/deps/build/destdir. This script mounts the LIVE source
@@ -10,15 +10,17 @@
 #
 # Usage (run on the build host, e.g. behemoth, from anywhere):
 #   scripts/docker-iter-build.sh
-#   IMAGE=snaporca-deps scripts/docker-iter-build.sh
+#   IMAGE=orcacad-deps scripts/docker-iter-build.sh
 #
 # On success the binary is inside the persistent volume at
 # /OrcaSlicer/build/package/bin/snapmaker-orca (copy it out with a follow-up
-# `docker run --rm -v snaporca_buildcache:/b alpine cp ...` or via this script's tail).
+# `docker run --rm -v orcacad_buildcache:/b alpine cp ...` or via this script's tail).
 set -euo pipefail
 
 REPO="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
-IMAGE="${IMAGE:-snaporca-deps}"
+# orcacad-deps, NOT snaporca-deps: see the note in kernel-test.sh — the wrong image
+# fails at CMake configure, not at link time.
+IMAGE="${IMAGE:-orcacad-deps}"
 BUILD_VOL="${BUILD_VOL:-orcacad_buildcache}"
 
 echo "REPO=$REPO  IMAGE=$IMAGE  BUILD_VOL=$BUILD_VOL"
@@ -32,6 +34,7 @@ docker run --rm \
   -v "$REPO/resources":/OrcaSlicer/resources \
   -v "$REPO/CMakeLists.txt":/OrcaSlicer/CMakeLists.txt \
   -v "$REPO/cmake":/OrcaSlicer/cmake \
+  -v "$REPO/deps_src":/OrcaSlicer/deps_src \
   -v "$BUILD_VOL":/OrcaSlicer/build \
   "$IMAGE" \
   bash -lc 'cd /OrcaSlicer && ./build_linux.sh -sr'

scripts/kernel-test.sh

@@ -22,7 +22,11 @@
 set -euo pipefail
 
 REPO="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
-IMAGE="${IMAGE:-snaporca-deps}"
+# orcacad-deps, NOT snaporca-deps: this fork is mainline-based and needs Eigen 5.0.1,
+# CGAL 5.6.3, wx 3.3.2 and Python 3.12 Development.Embed, none of which snaporca-deps has.
+# With the wrong image CMake dies at configure, which is exactly why this fork went
+# M1-M8 without ever compiling (see commit 1633005bba).
+IMAGE="${IMAGE:-orcacad-deps}"
 # Must NOT default to snaporca_buildcache: that is the other fork's volume, and pointing
 # this fork at it makes the two silently trade build artefacts. docker-iter-build.sh had the
 # identical defect and was fixed to orcacad_buildcache; this script was missed.

src/libslic3r/CadDocument.hpp

@@ -296,7 +296,13 @@ struct CadFeature {
     double rib_depth{10};       // extrude distance along the sketch-plane normal (mm)
 
     // --- Mate (assembly) ---
-    int    mate_kind{0};        // 0 = Fastened, 1 = Planar (M8b adds 2/3/4)
+    // 0 Fastened   — all 6 DOF fixed: B's frame is driven onto A's exactly.
+    // 1 Planar     — z axes aligned, normal distance set to mate_offset; in-plane position free.
+    // 2 Revolute   — axes collinear, position on the axis fixed; rotation about z free.
+    // 3 Slider     — orientation fully fixed, perpendicular position fixed; axial slide free.
+    // 4 Cylindrical— axes collinear, perpendicular fixed; both spin and axial slide free.
+    // A "free" DOF is preserved from the body's current placement, not zeroed.
+    int    mate_kind{0};
     int    mate_cs_a{-1};       // feature index of the FIXED CoordSys (mate connector A)
     int    mate_cs_b{-1};       // feature index of the CoordSys on the body that MOVES
     double mate_offset{0};      // translation along A's z, mm