Benchmark: the yang-gb1 benchmark asserts nothing about its result

Nobody has claimed this yet.

This issue was triaged from [`bugs/dan/0.5-Benchmark-package`](https://github.com/Macaulay2/M2/blob/388c1ff0ce30d83751dea7bc7eac77fdc1305dd7/bugs/dan/0.5-Benchmark-package), one of the 857 files removed from the pre-GitHub `bugs/` tree by [`d2c8d27826`](https://github.com/Macaulay2/M2/commit/d2c8d27826) and catalogued in [#36](https://github.com/Macaulay2/M2/issues/36). **The commentary below was written by Claude (Claude Opus 5, via Claude Code)**, not by @d-torrance, whose account posted it -- please weigh it accordingly.

### The original file, verbatim

```text
Benchmark package:

Example "yang-gb1" has no assertion to test the result.

Tests of the package should include running each the benchmarks.
```

### Where it stands today

Half done, by Dan himself.

**The tests half landed**: `8753fd3ae7` (2010) added `scan(keys benchmarks, b -> TEST("runBenchmarks "|format b))`,
so every benchmark now runs as a test — which is the file's second sentence.

**The assertion half did not.** `yang-gb1` still ends

```m2
(ti,re) := toSequence timing gb(J1); ti)
```

with no assertion about the result. So the benchmark measures how long a Gröbner basis computation takes
without checking that it computed the right thing — which is the file's first sentence, and the more
important half: a benchmark that silently computes the wrong answer looks like an improvement.

### Notes for whoever picks this up

The other benchmarks are worth a glance at the same time, since the file singles out `yang-gb1` only as
the example it noticed. An assertion here can be cheap — the number of generators of the result, or its
Betti numbers — without slowing the timing being measured.

_{`open` · disposition `issue` · source of truth: [`bug-triage/catalog.tsv`](https://github.com/d-torrance/M2/blob/bug-triage/bug-triage/catalog.tsv)}

Start with the `yang-gb1` benchmark and compare its result handling with the other benchmarks, then review the existing `runBenchmarks` test registration. Add a correctness assertion that does not affect the timing measurement, and run the benchmark package tests to confirm the result is checked.

Written by the indexing model from the issue text.