[MOBILE-APP] Full React Native Jest harness for host App (replace smoke-only suite)

[wheval]

Feature Description

@ancore/mobile-app currently runs a node smoke test because RN preset fails on Flow/ESM polyfills. Wire babel-jest + RN preset so App and navigation can be tested in CI.

Problem Statement

Host app has no real component coverage; regressions in onboarding shell will not be caught.

Proposed Solution

1. Configure babel-jest with @react-native/babel-preset.
2. transformIgnorePatterns for RN monorepo packages.
3. Restore/fix __tests__/App.test.tsx with testing-library.
4. Keep smoke as fallback only if needed.

Impact Area

• Mobile Wallet
• Developer experience

Priority

• Medium

Implementation Complexity

• Complex

[Okorie2000-code]

Hi Maintainer,

I'd like to work on this issue. I have experience with React Native, Jest, and CI testing. I can submit a clean PR within 48 hours.

[nurudeenheroic]

Hi @maintainer ! I've gone through the issue and understand what's required. I'm confident I can deliver an efficient solution that meets the expectations.