feat: data streams report verification contracts

[cl-mayowa]

Change Summary

1. Verifier contract: Six Tolk source files implementing EVM ABI payload parsing, secp256k1 signature recovery, signing hash computation, and oracle config management with duplicate-signer detection.
2. keccak256SnakeCell fix: Replaced a single-builder flatten (overflows at 1023 bits) with fixed-arity HASHEXT_KECCAK256 helpers that hash directly across N snake cells natively.
3. TypeScript wrapper: ContractClient providing typed send methods, getters, mirrored error codes/opcodes, and deterministic address computation via newFrom.
4. Blueprint config + codeLoader: Added Verifier.compile.ts and a dataStreams entry in codeLoader.ts that auto-compiles if the build artifact is missing.
5. Test suite: 47 functional tests (including a real production DON report) and 9 gas benchmarks across all config and verify operations.

[github-actions]

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