feat(standard-contracts): prototype C++-driven address derivation in bb

Adds a new `bb derive_standard_contract_addresses` subcommand that reads
freshly-built Noir artifacts and stamps the standard-contract addresses
into `standard_addresses.nr` (in both the aztec-nr/aztec crate and the
aztec_sublib twin) before the rest of noir-contracts compiles against
them. This breaks the build-order chicken-and-egg in the current TS-based
generator: the TS generator depends on the yarn-project build, but the
addresses need to be baked in before noir-contracts finishes.

For auth_registry and public_checks the derived address is byte-identical
to the TS-derived one (verified against the existing pinned values).

Known prototype limitations:
- `artifact_hash` and `private_functions_root` are READ from a sidecar
  manifest (`standard_contract_class_id_preimages.json`) instead of being
  derived from the artifact in C++. Porting their TS derivation
  (sha256-reduced-to-Fr merkle over selectors + metadata hashes, plus
  deterministic-JSON-stringify of contract outputs) is the natural
  follow-up.
- Bootstrap integration only handles auth_registry + public_checks;
  extending to multi_call_entrypoint is mechanical.
- The TS generator (`generate:data`) is left in place as a drift check —
  it still produces the same `standard_addresses.nr`, so any divergence
  fails the build loudly.

Author: dbanks12