feat(standard-contracts): pin compiled artifacts for release-branch reproducibility check

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Commits the freshly-built artifact JSON for each demoted standard contract (auth_registry, public_checks, multi_call_entrypoint) under yarn-project/standard-contracts/src/<name>/pinned/, plus a per-contract reproducibility.test.ts that compares the pinned artifact's sha256 against the freshly-built artifact's sha256.

The tests are it.skip(...)'d by default; CI on next stays green. To enable on a release branch, drop the .skip (or run the test manually: yarn workspace @aztec/standard-contracts test src/<name>/reproducibility.test.ts).

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• feat(standard-contracts): prototype C++-driven address derivation in bb #23350
• feat(protocol-contracts): autogen Noir interface stubs #23216
• feat(aztec-nr): introduce hand-written AuthRegistryInterface and PublicChecksInterface in aztec-nr #23256
• refactor(authwit): split into utils/private/public #23214
• feat(standard-contracts): pin compiled artifacts for release-branch reproducibility check #23262 👈 (View in Graphite)
• feat!: shift remaining protocol-contract addresses to 1-3 #23218
• feat!: demote multi_call_entrypoint to non-protocol contract #23197 : 1 other dependent PR (#23199 )
• feat!: demote public_checks to non-protocol contract #23217
• feat!: demote auth registry to non-protocol contract #23106
• refactor: move public_checks caller helpers into aztec-nr (prep for public_checks demotion) #23215
• merge-train/fairies

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