docs: update Zig 0.16.0 as stable and fix benchmark timing

[jinzhongjia]

Summary

Update documentation and benchmark implementation to reflect Zig 0.16.0 as a stable release, replacing the previous nightly/dev references.

Changes

• Documentation: Update all references from "0.16.0-dev (nightly)" to "0.16.0" across AGENT.md, CLAUDE.md, README.md, and README_CN.md
• CI/CD: Update tested versions to 0.14.1, 0.15.1, 0.16.0, and master
• Benchmarks: Refactor src/bench.zig to use std.Io.Clock.awake for timing in Zig 0.16+
  • Introduce BenchRuntime struct to hold the required std.Io context
  • Simplify getTimeNs() to use the stable Zig 0.16 API
  • Initialize runtime context in the Zig 0.16+ entry point

Notes

All changes maintain backward compatibility with Zig 0.14.x and 0.15.x versions.

[gemini-code-assist]

Code Review

This pull request updates the library's documentation and benchmarking logic to support Zig 0.16.0. The changes include updating version support tables in AGENT.md, README.md, and README_CN.md, as well as adapting the benchmarking timer in src/bench.zig to use the new std.Io APIs. Review feedback suggests that the usage of std.Io as a type and the specific API path for std.Io.Clock.awake may be incorrect, as std.Io is typically a namespace in the Zig standard library.

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src/bench.zig (21)

The type ?std.Io is likely invalid because std.Io is a namespace, not a type. If you intended to use a specific type from the std.io namespace, please correct the type definition. If std.Io is meant to be a custom type, ensure it is properly defined.

src/bench.zig (28)

The usage of std.Io.Clock.awake appears to be incorrect if std.Io is a namespace. Please verify the API path for accessing the clock in Zig 0.16+.