Allow small, medium and large engines

[ivpusic]

Updates dune query run and dune query run-sql to advertise --performance tiers as small|medium|large (including README and flag help text), replacing the previously documented free tier.

[cursor]

PR Summary

Low Risk
Primarily documentation/flag validation updates with added tests; behavior change is limited to accepting small and keeping free as a tolerated legacy value.

Overview
The CLI now advertises --performance tiers as small|medium|large (README and query run/query run-sql flag help), replacing the previously documented free tier.

Internally, parsePerformance is updated to validate small|medium|large while still accepting and forwarding legacy free; tests are adjusted to expect small and new coverage pins the free compatibility behavior.

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[charisra]

bugbot run

[cursor]

✅ Bugbot reviewed your changes and found no new issues!

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^{Reviewed by Cursor Bugbot for commit 0373515. Configure here.}