Incorporate google fuzztest

Track the work needed to incorporate https://github.com/google/fuzztest into the repository for future fuzz testing coverage.

This issue is meant to capture the follow-up effort required to:
- evaluate how `@google/fuzztest` fits into the current C++ test infrastructure
- identify any build, dependency, or tooling changes needed
- define a plan for adding fuzz tests to critical code paths
- determine whether additional CI support will be needed

Start by reviewing the repository's current C++ test infrastructure and how dependencies, build tooling, and CI are configured, then evaluate how @google/fuzztest fits those systems. Done means the required build, dependency, tooling, and CI changes are identified and a concrete plan exists for fuzz tests covering critical code paths.

Written by the indexing model from the issue text.