Add bulk UV sampler, TKHelix and MakeSphere (8.0.1.2)

- n3xd_ocp.sample.face_grid: a face's UV grid of points and outward
  normals in one GIL-free call, sampling exactly where np.linspace does
  so a caller's fitted surface does not move.
- n3xd_ocp.helix: OCCT 8.0's TKHelix, which upstream does not bind at
  all. Takes Python lists rather than NCollection_Array1. Two things the
  header does not say, both found by probing: SetParameters wants N+1
  diameters for N segments (one per boundary, so a taper interpolates),
  and the builder is right-hand only -- a negative pitch is error status
  12, not a mirrored helix.
- Bind BRepPrimAPI_MakeSphere and give inventory.py an EXTRA_SYMBOLS
  addendum for symbols no app source imports. assay's gen_flow_fixtures
  has been unrunnable since the 10C cutover for want of it; the gap was
  wider than --check, since sigdiff is inventory-driven too.

Gates: 105 tests, 139/139 symbols, sigdiff clean, ASAN clean, wheel
self-contained with no libGL/libX11 DT_NEEDED.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HbTQ2HYWQwdtGmGJwypt6Z

inventory.json

@@ -1,6 +1,6 @@
 {
-  "app_root": "/home/stroblme/n3xd/app/backend",
-  "files_importing_ocp": 115,
+  "app_root": "../app/backend",
+  "files_importing_ocp": 116,
   "modules": {
     "BOPAlgo": {
       "BOPAlgo_GlueShift": []
@@ -86,7 +86,8 @@
       "BRepPrimAPI_MakeCylinder": [],
       "BRepPrimAPI_MakeHalfSpace": [],
       "BRepPrimAPI_MakePrism": [],
-      "BRepPrimAPI_MakeRevol": []
+      "BRepPrimAPI_MakeRevol": [],
+      "BRepPrimAPI_MakeSphere": []
     },
     "BRepTools": {
       "BRepTools": [