Virtualize the installed-snaps list (ScrollView + .map) in SnapsSettingsList

> **Performance audit finding** · Severity: **Medium** · Effort: Easy · Fix risk: Simple · Test safety net: Uncovered
> Owner: `@MetaMask/core-platform`
> File: `app/components/Views/Snaps/SnapsSettingsList/SnapsSettingsList.tsx:40`

### What is this about?

`SnapsSettingsList` renders every installed Snap inside a plain `ScrollView` by
mapping over `Object.values(snaps)`. There is no virtualization, so all
`SnapElement` rows are mounted at once regardless of how many Snaps the user has
installed. For power users (or once more first-party Snaps ship) this mounts the
full list up front, paying the layout/mount cost for off-screen rows.

**Why it matters**

A `ScrollView` keeps every child mounted. Each `SnapElement` is a non-trivial
row (avatar/network image, text, navigation handler). As the installed-Snap
count grows, time-to-interactive for this settings screen scales linearly and
off-screen rows still consume memory and layout work. A `FlashList` would only
render the visible window.

### Scenario

N/A — see Technical Details.

### Design

N/A — internal performance change; no UI/design impact.

### Technical Details

**Evidence**

`app/components/Views/Snaps/SnapsSettingsList/SnapsSettingsList.tsx:38`
```tsx
return (


{(Object.values(snaps) as Snap[]).map((snap: Snap) => (

))}


);
```
`snaps` comes from `selectSnaps` (line 25), an unbounded controller-state map.

**Fix**

Replace the `ScrollView` + `.map()` with a `FlashList` (v2 — do not set
`estimatedItemSize`):
```tsx
const data = useMemo(() => Object.values(snaps) as Snap[], [snaps]);
return (

snap.id}
renderItem={({ item }) => }
/>

);
```
Keep `renderItem` and `keyExtractor` stable (module-scope or `useCallback`).

### Threat Modeling Framework

N/A — performance-only change; behavior is preserved, no new data flow / trust boundary / attack surface.

### Acceptance Criteria

- - Install many Snaps (or mock `selectSnaps` with 50+ entries) and confirm only
the visible rows mount (log in `SnapElement` or use React DevTools profiler).
- Confirm scrolling stays smooth and existing `SnapsSettingsList` behavior is
unchanged. No co-located unit test exists; add a render test asserting the
list renders provided Snaps.

### References

- File: `app/components/Views/Snaps/SnapsSettingsList/SnapsSettingsList.tsx:40`
- Source: MetaMask Mobile performance audit — finding `list-snaps-settings-scrollview-map`
- Owner (CODEOWNERS / best-effort): @MetaMask/core-platform
- Status: **UNVALIDATED**

Start with app/components/Views/Snaps/SnapsSettingsList/SnapsSettingsList.tsx, especially the selectSnaps usage and current ScrollView mapping. Replace the unvirtualized list as specified, then add a render test for provided Snaps and verify that many entries render only visible rows while existing behavior and scrolling remain unchanged.

Written by the indexing model from the issue text.