Bug: benchmark code has copy-paste errors — v6 benchmarks call `Version4::generate()`

[mnavarrocarter]

Context

tests/Benchmark/CastorVsRamseyBench.php contains copy-paste errors that invalidate several benchmarks:

• Lines 142 and 148: Methods named v6_generate_* call Version4::generate() instead of Version6::generate()
• Several Ramsey benchmarks call uuid1() instead of the version-appropriate function

This means the library's performance claims against Ramsey\UUID cannot be verified or trusted, since the benchmarks for v6 are actually measuring v4 generation. If the library is positioned as a faster alternative, these results need to be accurate.

Proposal

Fix all benchmark methods to call the correct UUID version class:

1. In v6_generate_to_string_castor() and v6_generate_to_string_ramsey(): use Version6::generate() and Uuid::uuid6()
2. Review all other version benchmarks (v1, v3, v5, v7) for similar copy-paste errors
3. After fixing, run the benchmarks and publish representative results in the README or a BENCHMARKS.md file
4. Consider adding a CI check that verifies benchmark method names match the version they are testing (e.g., a naming convention lint)