Mem-Client: High-Frequency Interaction Safety

High-frequency mem-client interaction handlers should be performance-safe.

Scope:
- Enforce when changing handlers for high-frequency events (scroll, resize, pointer/mouse move, key repeat, rapid input).

Rules:
1) Use appropriate throttling/debouncing/memoization where repeated work could cause visible jank.
2) Avoid expensive work on every high-frequency event when batching or guarding is feasible.
3) Include brief validation evidence for affected interaction smoothness when behavior changes materially.

Review behavior:
- Return NOT APPROVED when high-frequency handlers introduce obvious unbounded per-event heavy work.
- Do not block low-frequency event handlers.