Add Caching Layer

[SantamRC]

To improve performance add caching layer in the App wherever usefull.

[sahu-virendra-1908]

@SantamRC are you working on this? If not, please assign it to me.

[SantamRC]

Hi @sahu-virendra-1908 you are welcome to open PRs

[sahu-virendra-1908]

@SantamRC I carefully reviewed the existing codebase before implementing these changes and intentionally kept the solution minimal and production-focused.

Workflow followed:

Audited repeated network/API calls across frequently visited screens
Verified which areas were already cached before making changes
Avoided unnecessary architecture or state-management refactors
Added only lightweight in-memory TTL caching where repeated work was actually happening
Preserved the existing repository/service structure
Added cache invalidation for mutable flows (profile update, notifications, logout)
Avoided adding any new dependencies

The goal of this PR was to improve real-world performance with minimal safe changes rather than overengineering the app.

If you think any part can be improved further, I’d be happy to refine the implementation.