Confirm the casing of the ProjectHasNoApiAccess result code

[adamtheturtle]

The mock returns ProjectHasNoAPIAccess (src/mock_vws/_constants.py:64), but the VWS API Result Codes table spells it ProjectHasNoApiAccess. One of the two is wrong, and the value is user-visible in response bodies.

docs/source/differences-to-vws.rst already notes that this result code has not been verified against a real database in that state, so the casing has never been observed.

Acceptance criteria

• The casing is confirmed against a real database which has no API access, or the ambiguity is recorded in docs/source/differences-to-vws.rst.
• The mock matches whichever spelling real Vuforia returns.