Feature/offline support

[Nareshkumawat-star]

PR Description

This PR introduces robust offline support, an animated connectivity indicator, and smart data caching so users can continue reading articles even when they lose their internet connection.

Key Changes:

• Connectivity Indicator (OfflineBanner.tsx): A global, animated banner that slides down to inform the user when they are offline.
• Network Hook (useNetworkStatus.ts): Created a clean hook wrapped around @react-native-community/netinfo with full unit test coverage.
• Smart Caching (CacheUtils.ts): All successful API responses for Paginated Articles, Article Details, and Article Content are now securely cached locally using AsyncStorage.
• API Fallbacks: Modified React Query queryFn implementations for all core article hooks to gracefully catch network errors or offline states and automatically serve cached data instead of crashing or showing infinite spinners.
• Auto-Refresh Data (AppContent.tsx): The app monitors network state transitions; when transitioning from offline to online, it silently invalidates all queries to fetch the latest content in the background.
• Graceful Empty States (HomeScreen.tsx & ArticleScreen.tsx): If the user is completely offline and there is no cached data available for a particular view, they are presented with a friendly Offline UI state rather than a blank screen or a loading skeleton.

Type of Change

• Bug fix (change which fixes an issue)
• New feature (change which adds functionality)
• Documentation update

Select your work-area

• Frontend
• Backend
• Documentation
• Others

Related Issue

N/A

Fixes #1273

Checklist

• I have updated my branch and synced it with the project's 'develop' branch before making this PR.
• I have optimized the file changes.
• I have added a snapshot of my work example.
• I have made a PR to the project's develop branch.

Undertaking

• My code follows the style guidelines of this project.
• I have performed a self-review of my code.
• I have commented my code, particularly in hard-to-understand areas.

[github-actions]

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