DI: Replace Dispatchers.IO with injected CoroutineDispatcher

[ksharma-xyz]

TL;DR

Replaced hardcoded Dispatchers.IO with injected CoroutineDispatcher across ViewModels and network services.

What changed?

• Added CoroutineDispatcher as a constructor parameter to ViewModels and services
• Updated Koin DI modules to inject IODispatcher
• Removed direct Dispatchers.IO usage in favor of injected dispatcher
• Updated SplashViewModel, SavedTripsViewModel, ThemeSelectionViewModel, TimeTableViewModel, and RealTripPlanningService

Why make this change?

• Improves testability by allowing dispatcher injection
• Makes coroutine context usage more consistent across the codebase
• Follows dependency injection best practices
• Makes it easier to swap dispatchers for testing purposes

[ksharma-xyz]

• DI: Replace Dispatchers.IO with injected CoroutineDispatcher #506 👈 (View in Graphite)
• main

This stack of pull requests is managed by Graphite. Learn more about stacking.