v1.20250829.0

What's Changed

• [build] 08-28-25 build fixups by @fhanau in https://github.com/cloudflare/workerd/pull/4927
• update workerd-cxx and capnp-cpp by @anonrig in https://github.com/cloudflare/workerd/pull/4929

Full Changelog: https://github.com/cloudflare/workerd/compare/v1.20250828.1...v1.20250829.0