0.6.3 - Provider-reported token usage (tentative)

Adds provider-reported token usage to Choice, Score and Assessment results across Foundry, Ollama and Jev. Existing constructors remain available; missing counts remain null, reported zero is preserved, and totals are never inferred.

NuGet 0.6.3: core, Foundry, Ollama, Jev.

Publication and exact-version public-feed consumer verification succeeded in run 38644542842. Linux and Windows validation includes tests, formatting, coverage, samples, package metadata, symbols and Source Link.

Tentative early access: live Jev and local Ollama compatibility remains unverified. Token counts across models do not imply equivalent computation or cost. NuGet classifies 0.6.3 as stable because it has no prerelease suffix; this GitHub release is marked prerelease to retain the early-access notice.

Fix: #5. Addresses #4.