fix(layout): skip measurement while web container is hidden

[HuuNguyen312]

Description

Fixes #2522

On web, when a FlashList is mounted inside a container that becomes hidden (display: none, e.g. an inactive screen/column kept mounted), every DOM size reads as 0. If the list re-renders while hidden (data update, parent state change), the layout effects still run and:

1. measureParentSize returns a 0 x 0 window.
2. measureItemLayout returns height: 0 for every rendered item, overwriting the real measured heights.
3. The height average window (last 5 samples) drops to ~0, so every unmeasured item is also estimated at ~0.

With all layouts collapsed to y = 0, height = 0, getVisibleLayouts returns the entire data set as engaged, and the list mounts every item at once. In our chat app (~6,000 messages, inverted list) this froze the app on logout, when the chat screen is hidden but still mounted. Debug output captured at that moment:

engaged 0 5686 count 5687 data 6384 window {"width":0,"height":0}
measured 517 measuredZero 517
0:y=0,h=0 | 1:y=0,h=0 | 2:y=0,h=0 | ...

Fix

• Add isViewHidden(view) to measureLayout.web.ts: the container is hidden when both clientWidth and clientHeight are 0. The native implementation always returns false, so native behavior is unchanged.
• In RecyclerView, skip the container-measurement and item-measurement layout effects while the container is hidden, keeping the last valid layouts.
• While hidden, record a 0 x 0 container size so the existing onLayout size check sees a change once the container is shown again and triggers a fresh measurement.

Reviewers’ hat-rack 🎩

• On web, render a long list (thousands of items) inside a container, toggle the container to display: none, then update data while hidden. Before: every item renders. After: no extra items render.
• Show the container again: the list re-measures and renders normally at the same position.
• Native: no behavior change (isViewHidden always returns false).
• Unit tests added for isViewHidden (src/__tests__/measureLayout.web.test.ts). yarn test and yarn type-check pass; ESLint is clean on the changed files.