chore: update animation to pure black (#28731)

<!--
Please submit this PR as a draft initially.
Do not mark it as "Ready for review" until the template has been
completely filled out, and PR status checks have passed at least once.
-->

## **Description**

Updates the Market Insights animation to be pure Black.


https://github.com/user-attachments/assets/a2efcd50-9bac-4ced-838b-2e9da5c5f304

<img height="800" alt="Simulator Screenshot - iPhone 16e - 2026-04-13 at
14 15 36"
src="https://github.com/user-attachments/assets/f23cd7b4-e3e1-4622-80d8-aa4f98f61621"
/>



## **Changelog**

<!--
If this PR is not End-User-Facing and should not show up in the
CHANGELOG, you can choose to either:
1. Write `CHANGELOG entry: null`
2. Label with `no-changelog`

If this PR is End-User-Facing, please write a short User-Facing
description in the past tense like:
`CHANGELOG entry: Added a new tab for users to see their NFTs`
`CHANGELOG entry: Fixed a bug that was causing some NFTs to flicker`

(This helps the Release Engineer do their job more quickly and
accurately)
-->

CHANGELOG entry: null


## **Related issues**

Fixes:

## **Manual testing steps**

```gherkin
Feature: my feature name

  Scenario: user [verb for user action]
    Given [describe expected initial app state]

    When user [verb for user action]
    Then [describe expected outcome]
```

## **Screenshots/Recordings**

<!-- If applicable, add screenshots and/or recordings to visualize the
before and after of your change. -->

### **Before**

<!-- [screenshots/recordings] -->

### **After**

<!-- [screenshots/recordings] -->

## **Pre-merge author checklist**

- [ ] I've followed [MetaMask Contributor
Docs](https://github.com/MetaMask/contributor-docs) and [MetaMask Mobile
Coding
Standards](https://github.com/MetaMask/metamask-mobile/blob/main/.github/guidelines/CODING_GUIDELINES.md).
- [ ] I've completed the PR template to the best of my ability
- [ ] I've included tests if applicable
- [ ] I've documented my code using [JSDoc](https://jsdoc.app/) format
if applicable
- [ ] I've applied the right labels on the PR (see [labeling
guidelines](https://github.com/MetaMask/metamask-mobile/blob/main/.github/guidelines/LABELING_GUIDELINES.md)).
Not required for external contributors.

## **Pre-merge reviewer checklist**

- [ ] I've manually tested the PR (e.g. pull and build branch, run the
app, test code being changed).
- [ ] I confirm that this PR addresses all acceptance criteria described
in the ticket it closes and includes the necessary testing evidence such
as recordings and or screenshots.

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> **Low Risk**
> UI-only changes to the Market Insights header animation/skeleton; main
risk is minor visual regressions or layout issues across device sizes
due to the new aspect ratio and gradient overlay.
> 
> **Overview**
> Tweaks the Market Insights hero animation area by reducing its height
(updates the aspect ratio in both the real view and its loading
skeleton).
> 
> Adds a `LinearGradient` overlay at the bottom of the background video
to fade into the current theme background color (improving the
transition to a pure-black background).
> 
> <sup>Reviewed by [Cursor Bugbot](https://cursor.com/bugbot) for commit
0fe7d3a. Bugbot is set up for automated
code reviews on this repo. Configure
[here](https://www.cursor.com/dashboard/bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Author: zone-live

app/components/UI/MarketInsights/Views/MarketInsightsView/MarketInsightsView.tsx

@@ -16,6 +16,7 @@ import {
   useColorScheme,
 } from 'react-native';
 import Video from 'react-native-video';
+import LinearGradient from 'react-native-linear-gradient';
 // eslint-disable-next-line @typescript-eslint/no-require-imports, @typescript-eslint/no-var-requires, import-x/no-commonjs
 const MarketInsightsBackgroundVideoLight = require('../../animations/market-insights-background-light.mp4');
 // eslint-disable-next-line @typescript-eslint/no-require-imports, @typescript-eslint/no-var-requires, import-x/no-commonjs
@@ -619,7 +620,7 @@ const MarketInsightsView: React.FC = () => {
         contentContainerStyle={tw.style('pb-4')}
         showsVerticalScrollIndicator={false}
       >
-        <Box twClassName="w-full" style={{ aspectRatio: 786 / 340 }}>
+        <Box twClassName="w-full" style={{ aspectRatio: 786 / 240 }}>
           {showLastFrame && (
             <Image
               source={lastFrameImage}
@@ -642,6 +643,13 @@ const MarketInsightsView: React.FC = () => {
               testID={MarketInsightsSelectorsIDs.BACKGROUND_ANIMATION}
             />
           )}
+          <LinearGradient
+            colors={[
+              `${theme.colors.background.default}00`,
+              theme.colors.background.default,
+            ]}
+            style={tw.style('absolute bottom-0 left-0 right-0 h-16')}
+          />
         </Box>
         <AnimatedSection delay={SECTION_ANIMATION_DELAYS_MS.topArticle}>
           <Box twClassName="px-4 pt-4 pb-3">

app/components/UI/MarketInsights/Views/MarketInsightsView/MarketInsightsViewSkeleton.tsx

@@ -30,7 +30,7 @@ const MarketInsightsViewSkeleton: React.FC<MarketInsightsViewSkeletonProps> = ({
       >
         <Skeleton
           width="100%"
-          style={tw.style('w-full', { aspectRatio: 786 / 340 })}
+          style={tw.style('w-full', { aspectRatio: 786 / 240 })}
         />
 
         <Box twClassName="px-4 pt-4 pb-3" gap={2}>