Update gnark recursive verifier for new whir API

[Bisht13]

The whir dependency was updated in #288 to support the new transcript API (PR #215) and weights trait API (PR #217).

The Go gnark recursive verifier (tooling/provekit-gnark/) still references the old whir config struct fields and needs to be updated to match.

What needs updating

• tooling/provekit-gnark/src/gnark_config.rs — reads whir config fields for the Go side
• Go verifier circuit logic to match any protocol-level changes in proof serialization

Context

• whir rev: 3056565b90931c28f725f6655d954bd8f17eaaf6
• Provekit PR: Port to whir PR #215 + PR #217 with Skyscraper HashEngine #288