10C Inc 1: core modeling

Binds the modeling core the app builds every feature out of — 93 of its 138
symbols now resolve, up from 34. New modules: GeomAbs, Geom2d, Geom,
TCollection, TColgp, TColStd, GProp, BRepGProp, Bnd, BRepBndLib, Adaptor3d,
BRepAdaptor, GeomLProp, GeomAPI, BRepBuilderAPI, BOPAlgo, BRepAlgoAPI,
BRepPrimAPI, GC, BRepMesh; gp and BRep_Tool completed.

Three structural decisions:

- BRepBuilderAPI_MakeShape carries Build/Shape/Generated/Modified/IsDeleted for
  every maker in the binding, so the booleans, the primitives and (later) the
  fillet builders all answer the app's duck-typed provenance layer through
  ordinary virtual dispatch. History lists come back copied, so they outlive
  the builder.
- The executing two-argument BRepAlgoAPI constructors stay unbound; operands go
  in through SetArguments/SetTools. Section keeps Init1/Init2, which are plain
  setters. BOPAlgo moved up from Inc 2 — SetGlue needs its enum.
- Adaptor3d is registered although the app never imports it: every method it
  calls on BRepAdaptor_Curve/Surface is a virtual declared there, so binding
  them once on the bases leaves mod_BRepAdaptor.cpp with just constructors.

Gate: tests/test_inc1_modeling.py against reference values gen_fixtures.py now
records from the stock wheel — measurements, per-face area/centroid in map
order, mesh counts, and the boolean history map compared exactly, since that is
the substrate the app's topological naming is built on.

tools/sigdiff.py compares our bound surface against stock's, because a wrong
nb::init<> is silent: MakePrism's five-argument form bound OCCT's semi-infinite
gp_Dir overload (gp_Dir converts from gp_Vec), producing a valid solid of the
wrong shape with the flags shifted along. The fixture digest caught it; sigdiff
finds the class of bug directly, and now reports only one deliberate deviation.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DfriM8XUkn7uYf5Dwe2xo6

Makefile

@@ -32,6 +32,18 @@ dev: ## Incremental build + run the test suite (the inner loop)
 
 test: dev ## Alias for dev
 
+check: ## Coverage of the app's symbol inventory, against the in-container build
+	$(DOCKER_RUN) /cache/venv/bin/python /io/tools/inventory.py --check \
+		--inventory /io/inventory.json
+
+sigdiff: ## Diff our bound surface against the stock wheel's (needs the app venv)
+	cd $(REPO)/../app && uv run --project backend python \
+		$(REPO)/tools/sigdiff.py --dump $(CACHE)/sig-stock.json
+	$(DOCKER_RUN) /cache/venv/bin/python /io/tools/sigdiff.py \
+		--dump /cache/sig-ours.json
+	python3 $(REPO)/tools/sigdiff.py --compare \
+		$(CACHE)/sig-stock.json $(CACHE)/sig-ours.json
+
 shell: ## Interactive shell in the builder image
 	docker run --rm -it -v $(REPO):/io -v $(CACHE):/cache $(IMAGE) bash