fix(ci): stop the ASR test failing on decodes that got no worse

[tawei-amd]

Summary

The ASR test (#799) failed PR #798 on Windows HRX (run 38939931243) with "no more runaways than the baseline: 4 vs 3". That was a false positive:

Build	de-fleurs-02 transcript	Errors
main	the first half repeated twice, the second half missing	12
#798	the same repeated first half, plus the correct second half	12

The extra correct words pushed #798's transcript past 1.5× the reference length, which is the runaway threshold. The loop itself is main's decoder bug and occurs in both builds. The flip between them comes from #798's FFT change on a borderline HRX decode.

Changes (.github/script/asr_test.py)

• Runaways and repeated phrases. A file only counts against a build if it became a runaway (or repeats more phrases) and also has more errors than in the baseline. The check is renamed "no new runaway transcripts" and names the files when it fails.
• Per-set limit only for sets of ten or more files. A single long-form file moves by many points whenever one decode flips, and HRX builds flip between identical runs: main's own Linux HRX build scored 18.5% and 36.8% on en-longform. The long-form sets are still covered by the pooled rate and by the two checks above.

Test plan

• Replayed the new comparison against every CI result so far: fix: replace FFTW with pocketfft and ship third-party notices #798 run 38939931243 and ci: add ASR test workflow for Whisper transcription #799 run 38930074515, four platforms each. All pass, including fix: replace FFTW with pocketfft and ship third-party notices #798 on Windows HRX.
• Replayed against local runs of Support OpenAI verbose_json for /v1/audio/transcriptions (+ multipart field fix) #510, fix(whisper): make the ASR decode loop behave like Whisper #794 and fix: replace FFTW with pocketfft and ship third-party notices #798 against main: all pass the core checks.
• A synthetic new loop with more errors (es-fleurs-03) still fails, naming the file.
• ASR Test on this PR.

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