Fix Osaka playground compilation

[eitjuh]

Summary

Fixes playground compilation when Osaka is selected by mapping the Osaka hardfork to the latest EVM target supported by the pinned Solidity compiler.

Solidity 0.8.27 supports prague as an EVM target, but not osaka, so passing osaka caused compilation to fail with Invalid EVM version requested.

Test plan

• Open /playground
• Keep the default Osaka fork selected
• Press Run
• Confirm compilation succeeds instead of failing with Invalid EVM version requested

[vercel]

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[cursor]

PR Summary

Low Risk
Single-branch change in fork-to-EVM mapping; no auth, data, or runtime execution logic affected.

Overview
Maps the Osaka hardfork to the prague Solidity EVM target in getTargetEvmVersion, alongside the existing EOF mapping.

With Solidity 0.8.27 pinned in the playground, selecting Osaka (the default fork) previously passed osaka as evmVersion and failed compilation with Invalid EVM version requested. Osaka now compiles using the highest EVM version that compiler supports.

^{Reviewed by Cursor Bugbot for commit b7c4808. Configure here.}