v1.20260121.0

What's Changed

• update-deps.py: Allow bazel_dep + archive/git_override by @npaun in https://github.com/cloudflare/workerd/pull/5876
• tune tcmalloc for benchmarks by @anonrig in https://github.com/cloudflare/workerd/pull/5903
• EMAIL-1332: Add Email MessageBuilder types by @Skye-31 in https://github.com/cloudflare/workerd/pull/5929
• improve streams queue test harness by @anonrig in https://github.com/cloudflare/workerd/pull/5930
• Add tests for internal stream error paths by @anonrig in https://github.com/cloudflare/workerd/pull/5931
• Fix: Make it impossible to load dynamically generated shared libraries by @hoodmane in https://github.com/cloudflare/workerd/pull/5910
• chore: Remove Rc Ref from workerd by @tewaro in https://github.com/cloudflare/workerd/pull/5938
• Add tests for stream controller error paths by @anonrig in https://github.com/cloudflare/workerd/pull/5933

Full Changelog: https://github.com/cloudflare/workerd/compare/v1.20260120.0...v1.20260121.0