MVP 3: Direction-aware navigation

[saadkhalidkhan]

Summary

• Add NavAnimation.directionAware(forward, backward) to map forward push transitions and backward pop transitions without stack-depth tracking.
• Extend sample app with Home → Details → Checkout flow using slideLeft forward and slideRight backward.
• Add unit tests for transition mapping with presets and custom animations.

Test plan

• ./gradlew :nav-animation:testDebugUnitTest
• ./gradlew :app:assembleDebug
• Manual: open Direction-aware checkout in sample app, navigate forward to Checkout, pop back twice and confirm reverse slide

Made with Cursor