Authenticated remote OpenViking servers derive tenancy from the Bearer
key, but the client was always sending X-OpenViking-Account and
X-OpenViking-User — defaulted to the literal string "default" — which
overrode the key-derived tenant and broke auth.
- _headers(): skip X-OpenViking-Account/-User when blank or "default"
(treats the legacy default value as unset, so existing installs don't
need to touch their .env)
- _headers(): send Authorization: Bearer <key> alongside X-API-Key for
standard HTTP auth compatibility
- health(): include auth headers so /health works against servers that
require authentication
Tests cover bearer emission, legacy "default" suppression, empty
suppression, real tenant passthrough, and authenticated health checks.
Fixes the same user report as #20695 (from @ZaynJarvis); that PR could
not be merged because its branch was stale against main and would have
reverted recent OpenViking work (#15696, local resource uploads, summary
URI normalization, fs-stat pre-check).