Task: Standardize native and engine failure injection controls for tests

[RtlZeroMemory]

Parent EPIC: #324

Problem:

Native and engine error paths need a deliberate way to be exercised from the test harness.

Scope:

• Define supported controls for native and engine validation failures, buffer limits, and related errors.
• Make the controls available to the harness stack.
• Keep the result contracts explicit.

Done when:

• Tests can trigger native and engine failures through supported controls.
• Critical native error paths can be covered without ad hoc setup.

Notes:

• This task should produce work that is reviewable against expected behavior, not current implementation shape.
• Keep outputs straight to the point and tied to repo code or repo process.

[RtlZeroMemory]

Implemented in #367.

Added a reusable configurable native shim in packages/node/src/__tests__/worker/testShims/configurableNative.ts and focused worker integration coverage.

This now pins:

• reported terminal capabilities can be overridden deterministically in backend tests
• engine present failures surface as backend fatals through the real worker path

Verified with:

• ./node_modules/.bin/tsc -b packages/core/tsconfig.json packages/node/tsconfig.json --pretty false
• node --test packages/node/dist/__tests__/worker_integration.test.js

Still unresolved:

• no speculative buffer-overflow hook was added beyond the current meaningful worker/native error surfaces