docs: lead Quickstart with pytest path and expected output

[AshSgDe29071999]

Summary

Improves the README Quickstart so the first copy-paste path is offline pytest -q with concrete expected output, plus a shaped hash-embedder benchmark table, before model-download commands.

What readers get

• Install + pytest -q with the expected dots/[100%] line
• Offline tenantq benchmark --embedder hash with the real report shape (modes, columns)
• Full fastembed path and a sample search command after that

Test plan

• Docs-only; commands match project layout and a local hash benchmark run

Fixes #1

[royalpinto007]

Thanks! Could you fix the Quickstart so the documented search command works after the benchmark, and update the expected pytest output to match the current seven tests? Please ping me once updated.