[6.3] Story: Migrate r4r-app

[adriancofie]

Description

Update r4r-app to consume @nciocpl/react-app-shared.

Parent Issue: #EPIC_6

Sub-Tasks

• Install @nciocpl/react-app-shared
• Replace Spinner with shared version
• Replace ErrorBoundary with shared version
• Create adapter for Pager callback (different signature)
• Update imports
• Verify tests pass
• Remove deprecated local components

Notes

• r4r-app uses different callback signature for Pager - adapter needed