The browser's local-development session-proof short-circuit tested
`!route.certificate`, while the shared verifier already treated an empty or
whitespace signature as unsigned, matching C# `Verify` (`:120`). A loopback
route carrying a blank-signature certificate therefore passed the verifier
and was then refused for lacking a provider key, where C# returns
`IsLocalDevelopment` and skips the session proof.
`isUnsignedCertificate` in `cultnet-ts/authority` is now the one owner of
that reading; the verifier and the browser both call it. A browser test pins
the local-development loopback open without a provider proof, the signed
loopback certificate still demanding it, and the remote counterpart refused
in both trust modes. The mutation runner gains two predicate mutations
(whitespace treated as signed; only a missing certificate treated as
unsigned), both killed by the existing whitespace-signature test in
cultnet-ts.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
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