follow-up: complete jina-base (768d) embedding Hit@k benchmark for v3.10.1 dogfood report

[carlos-alm]

Deferred from PR #1180 review.

Original reviewer comment: #1180 (comment)

Context: The Phase 8 embedding-benchmark table in generated/dogfood/DOGFOOD_REPORT_v3.10.1-dev.80.md published the jina-base (768d) row with a placeholder ("benchmark still running at report cut"). Greptile flagged that an incomplete data point in an official report is misleading.

The follow-up work is:

1. Finish the jina-base Hit@1/Hit@3/Hit@5 run on the same 1500-sample corpus used for minilm and jina-small.
2. Either:
   • Backfill the numbers into the v3.10.1-dev.80 report (preferred — keeps the historical record intact), or
   • Open a small addendum file under generated/dogfood/ linking back to the original report.
3. Update §8 "Benchmark Assessment" to compare jina-base vs jina-small / minilm once the data is in.

For the in-flight PR #1180, the row has been clarified as "not completed — see this issue" so reviewers don't read it as suppressed data.