ci: add a ci build step for vite to ensure the library builds

[satya164]

Description

This adds a vite setup and CI build step to ensure that the library builds for Web with vite to avoid regressions.

Changes

• Updated react-native-builder-bob to use its vite config
• Added index.html, vite.config.mjs and required deps for vite
• Replaced usage of useAnimatedValue and added PlatformColor fallback in examples since they are not exported from react-native-web
• Added icons without scale so vite can resolve them

Before & after - visual documentation

CleanShot.2026-05-11.at.12.36.22.mp4

Test plan

CI workflow is added, which runs yarn build:web under FabricExample/

Checklist

• Included code example that can be used to test this change.
• For visual changes, included screenshots / GIFs / recordings documenting the change.
• For API changes, updated relevant public types.
• Ensured that CI passes