Bump to OCCT 8.0.1

Four mechanical binding edits; the bound Python surface is unchanged
(sigdiff compared the 7.9.3.1 dump against 8.0.1.1's in both directions
and found no class, member or constructor arity moved), so the app needs
no change.

- NCollection_Utf8String is gone; NCollection_String is the same UTF-8
  type. Python name kept, since the app imports it.
- Standard_Failure lost its Standard_Transient RTTI when it moved to
  deriving std::exception; ExceptionType() replaced DynamicType()->Name()
  and returns the same class names the exception dispatch keys on.
- FindKey gained a size_t overload beside the int one, so the plain
  member pointer is ambiguous; overload_cast picks the int form, which
  keeps the negative-index guard.
- StdPrs moved from TKService to TKV3d, so CMakeLists links both.

The byte-identity fixtures did NOT retire, contrary to the watchlist:
all six round-trip to the same digests under the new kernel, as do the
measurement, history and mesh-count blocks, so tests/data is untouched
and the app's content-addressed BREP payloads stay valid.

Gates: binding suite 83 passed, 138/138 symbols, sigdiff clean both
directions, ASAN clean, app suite 1798 passed / 1 skipped (unchanged),
sweep over 4486 parts with anchors_digest and every status unchanged,
-m perf 16% faster on the 32-feature chain.

tools/parity_venv.sh

@@ -57,8 +57,9 @@ else
 fi
 
 # Everything below runs the venv's interpreter directly.  `uv run` would re-sync
-# the environment against the app's manifest first, which still asks for
-# cadquery-ocp-novtk — reinstalling it on top of the swap.
+# the environment against the app's manifest first, reinstalling the pinned
+# version on top of the swap — which across a kernel bump means silently
+# testing the old OCCT while believing you are on the new one.
 echo "--- sanity ---"
 # Asserted, not printed: __occt_version__ exists only on our wheel, so this is
 # also the check that the swap landed in the environment we meant.