Task: Add failure and fallback scenarios for modal and table/tree flows

[RtlZeroMemory]

Parent EPIC: #324

Problem:

Modal and collection widgets need failure-path coverage for focus, layering, scrolling, and resize-sensitive cases.

Scope:

• Write scenarios for modal, table, tree, and related flows under degraded or failing conditions.
• Cover the visible behavior that must still hold.
• Reuse the shared harness stack and capability profiles.

Done when:

• Modal and table/tree flows have explicit failure and fallback scenario coverage.
• At least the main release-critical failure paths are pinned.

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 terminal-real scenario coverage for:

• modal blocking plus focus restore under reduced capabilities
• virtual-list interactivity after repeated resizes

This now pins:

• the modal still blocks background typing and focus returns to the input after close on a reduced-capability terminal path
• repeated resize storms do not wedge the virtual-list flow, and later keyboard activation still succeeds

Verified with:

• node --test packages/node/dist/__tests__/ptyScenario.test.js
• node --test packages/core/dist/testing/__tests__/referenceScenario.semantic.test.js

Still unresolved:

• tree failure presentation remains under-specified, so no strict visible tree-failure assertions were added here