Add VuMark to endpoint fixture for auth testing

[adamtheturtle]

Summary

Adds VuMark instance generation endpoint to the parametrized endpoint fixture, enabling all existing auth tests to cover VuMark. Updates the Endpoint class to support endpoints that return binary data on success by making successful_headers_result_code optional. Updates test_date_header.py to properly handle VuMark's binary response format.

Changes

• Adds vumark_generate_instance fixture in prepared_requests.py following the same pattern as other endpoints
• Makes successful_headers_result_code: ResultCodes | None in Endpoint class to accommodate non-JSON responses
• Adds VuMark to the parametrized endpoint fixture params in conftest.py
• Updates test_date_header.py success assertions to handle None result codes

🤖 Generated with Claude Code

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Note

Medium Risk
Touches core request validation/error-shaping and broadens multiple parametrized test suites, so mismatched endpoint detection or result-code handling could cause regressions across many service endpoints.

Overview
Adds the VuMark instance-generation endpoint (POST /targets/<id>/instances) to the shared parametrized endpoint fixture so existing auth/date/invalid-JSON tests run against VuMark as well.

Updates test utilities and assertions to handle VuMark’s binary success responses by allowing Endpoint.successful_headers_result_code to be None and skipping JSON result_code assertions in test_date_header. Separately, aligns mock service validation to return Vuforia’s BadRequest result_code for invalid JSON specifically on the /instances route by introducing ResultCodes.BAD_REQUEST, adding BadRequestError, and routing validate_json errors based on request_path.

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