fix: populate comparison table throughput with current perf data format

Same schema drift as the scatter charts: the comparison table only
looked for scale-suffixed feature names (cell_values_10k, etc.) and
required op_count for rate calculation.

- Add "cell_values" fallback to read/write scenario lookups
- _fmt_rate now computes ops/s when op_count is absent
- Regenerate dashboard HTML

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: wolfiesch