Resolve CodeQL go/path-injection (alert #96): the certFile path from
the getCertHash endpoint flowed straight into os.ReadFile, letting an
authenticated request read arbitrary files by path. Validate it against
an allow-list of certificate files the panel already references (inbound
TLS certificateFile values plus the panel's own web cert) and read the
config-sourced path rather than the caller-supplied one, breaking the
taint flow while preserving arbitrary cert locations.
33b029e1ca