The public key decoding from JWKS was missing base64url padding, causing
JWT signature verification to fail with "invalid jwt token" errors in
production. The `jwk.x` value needs proper padding before base64 decoding.
Fixed by using the existing `base64urlDecode` helper function which
correctly adds padding, instead of manually doing the conversion.
This resolves JWT verification failures when REQUIRE_SIGNED_DEBUG_REQUESTS
is enabled.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
