- internal/middleware/operator_bearer.go: returns 404 on miss (NOT 401)
per spec §11.5; subtle.ConstantTimeCompare for timing safety; rejects
when configured token is empty (defense-in-depth even though wire-up
skips mount in that case).
- Table-driven test covers: missing header, empty header, wrong scheme
(Basic), case-sensitive scheme (lowercase bearer), no payload,
no-space-after-Bearer, equal-length wrong token, different-length
wrong token, correct token, empty-config rejects both empty and
populated headers, extra-whitespace rejection. Also asserts no
WWW-Authenticate header on 404 (endpoint-hiding intent).
- config.OperatorConfig + OPERATOR_TOKEN env mapping; default empty
(mount is skipped when empty).