feat(berachef): override abi generation for backwards compatibility

[SnowBera]

Summary

Bepolia uses the upgraded BeraChef interface while mainnet still uses the legacy interface. Add a temporary generation override so the existing beraChefAbi export includes both versions.

What's Changed

• Preserve legacy exemption methods, events, and errors while adding the upgraded exemption and vault eligibility methods.
• Append missing entries without duplicating or replacing existing definitions; fail generation on conflicting definitions.
• Apply the override only to the current BeraChef contract in the contracts source.

Consumers must retain fallback handling for methods unavailable on their deployed contract. Remove the override once mainnet is upgraded, the configured source generates the upgraded ABI, and consumers stop calling legacy methods.