Remove shadowed abyss-machine helpers

[8Dionysus]

PLAN

Remove the two shadowed helper definitions from artifact_bundles.py and memory_adapters.py, preserving the active implementations. Refresh the generated ABI digest that covers these source files.

DIFF

• Removed only the unreachable duplicate _string_list and _kib_to_mib definitions.
• Kept the later active implementations and all call sites unchanged.
• Regenerated generated/contract_abi_signatures.min.json.
• No installed host, service, or runtime state changed.

VERIFY

• tests/public_smoke/test_memory_adapters.py: 16 passed
• artifact trust smoke suite: 285 passed
• full owner validation graph: passed (sufficient=true)
• public boundary, scaffold index, ABI digest, and git diff --check: passed
• Checkpoint review: agent-review:f2fd358a:20260907T235525Z

LIVE HOST EVIDENCE

No live host mutation or service restart performed.

REPORT

This is a source and generated-digest change only. Installed CLI/consumer update is a separate post-merge decision.

RESIDUAL RISK

GitHub Repo Validation is the authoritative landing check; installed-host parity and runtime health remain separate claims.