feat(mobile): use react-native-ease for Fallback shimmer

[AndreiCalazans]

Uses react-native-ease for the Fallback shimmer. It runs the animation on the UI thread through the native platform animation modules, so it does not block the JS thread.

This also opens the door to improving other animated CDS mobile components.

Reference implementation: https://coinbase.ghe.com/consumer/react-native/pull/75520

Why react-native-ease: https://andrei-calazans.com/posts/2026-07-15-which-react-native-animation-library/

Simulator.Screen.Recording.-.iPhone.17.Pro.-.2026-08-05.at.18.39.23.mov

[cb-heimdall]

🟡 Heimdall Review Status

Requirement	Status	More Info
Reviews	🟡 0/1	Denominator calculation Show calculation 1 if user is bot 0 1 if user is external 0 2 if repo is sensitive 0 From .codeflow.yml 1 Additional review requirements Show calculation Max 0 0 From CODEOWNERS 1 Global minimum 0 Max 1 1 1 if commit is unverified 0 Sum 1
CODEOWNERS	🟡 See below

🟡 CODEOWNERS

Code Owner	Status	Calculation
ui-systems-eng-team	🟡 0/1	Denominator calculation Additional CODEOWNERS Requirement Show calculation Sum 0 0 From CODEOWNERS 1 Sum 1

[AndreiCalazans]

Heads up for reviewers: this is a fork PR, so the following checks fail for infra/policy reasons, not code:

• Visreg iOS/Android — BROWSERSTACK_* / PERCY_TOKEN secrets are not exposed to fork PRs, so the visreg job exits early. Please re-run with secrets. The shimmer render changes, so new Percy baselines will need approval.
• StepSecurity / Heimdall — require maintainer approval for an external contributor.

All code checks pass: Test, Typecheck, Lint, Format, Depcheck, Build, Bundle Stats, dry-run-publish, Validate.