fix: SL-323: login screen design fixes (#22781)

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## **Description**
Login screen design fixes:
* Replace metamask wordmark animation with static logo.
* Change background color to same as in live app
* resolve spacing issue in b/w login option switch and unlock button.

Jira: https://consensyssoftware.atlassian.net/browse/SL-326,
https://consensyssoftware.atlassian.net/browse/SL-323
BugFix: #22770,
#22846

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## **Changelog**

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CHANGELOG entry: null

## **Related issues**

Fixes:
Login screen design fixes:
* #22770
* #22846

## **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**


https://github.com/user-attachments/assets/485fd6cc-40bd-4ade-a040-409d7168b566

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

### **After**


https://github.com/user-attachments/assets/92b33de7-466e-48cd-8701-44ce6caec6f9



https://github.com/user-attachments/assets/13372206-c9de-47ca-a22a-d686b55e494b

<img width="304" height="637" alt="Screenshot 2025-11-17 at 5 25 08 PM"
src="https://github.com/user-attachments/assets/b0cd96fb-a804-496f-a34d-a9d1e17e8ec8"
/>



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

## **Pre-merge author checklist**

- [x] 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).
- [x] I've completed the PR template to the best of my ability
- [x] I’ve included tests if applicable
- [x] I’ve documented my code using [JSDoc](https://jsdoc.app/) format
if applicable
- [x] 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**

- [x] I've manually tested the PR (e.g. pull and build branch, run the
app, test code being changed).
- [x] 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]
> Replaces onboarding wordmark animation with a static MetaMask logo,
starts fox animation on mount, simplifies background handling, and
adjusts spacing/layout with corresponding test updates.
> 
> - **Login UI (`app/components/Views/Login`)**
> - Replace `OnboardingAnimation` with static MetaMask wordmark image
(`METAMASK_NAME`).
>   - Start `FoxAnimation` on mount (`setStartFoxAnimation('Start')`).
> - Remove theme-based SafeAreaView background override; rely on default
theme colors.
> - Layout tweaks: top padding, align content to `flex-start`, add
margins for logo/field, add `unlockButton` top margin.
> - Simplify text field styling (remove `textField` background override)
and keep error/help/biometry flows intact.
> - **Styles (`styles.ts`)**
> - Add `metamaskName` style; adjust `container`, `field`, and CTA
spacing; remove unused `ctaWrapper*` and theme-dependent `textField`
color.
> - **Tests**
> - Update snapshots to reflect new layout/logo and removed background
override.
> - Remove style-specific tests; add checks for static logo presence and
100ms seedless-password check timing.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
d0fa9ba. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Author: grvgoel81