Fix #81: Add Chang HF SOP User Story coverage

[lemayan]

1. Audited Existing Tests: We first checked the codebase and confirmed that 3 out of the 4 features (Keccak256, Blake2b-224, and Bitwise operations) were actually already implemented and tested.
2. Identified the Gap: We found that the last feature, CIP-85 (Sums-of-products), was completely missing. ("Sums-of-products" is just a new, optimized way for smart contracts to handle and store complex data more efficiently, saving users money on fees).
3. Wrote the Missing Test: We created a brand-new Plutus smart contract and a corresponding end-to-end test that specifically uses this new "Sums-of-products" feature.
4. Integrated the Test: We hooked this new test into the main test suite (specifically the Conway era tests, which is where this new feature actually goes live) so it will automatically run whenever the code is tested.

[lemayan]

The code is fully updated for Chang/Conway, but I'm unable to get the E2E testnet to finish within the GitHub Actions runner timeout limits