Closes#273
Verify inference endpoints synchronously on the server during set/update, expose a --no-verify escape hatch in the CLI and Python helper, and return actionable failures when validation does not pass.
The strip_headers list in send_backend_request included default_headers
names (e.g. anthropic-version), which removed the client's value. The
already_sent check then saw the original input still contained the header
and skipped injecting the route default. Neither value reached upstream.
Remove default_headers names from strip_headers so client values pass
through. The existing already_sent guard still injects defaults only when
the client omits them.
Piotr Mlocek