test: coverage for Onboard and Home screens.

[isaacsa51]

Description

Decoupled BudgetViewModel into 4 focused controllers with full unit test coverage, refactored the Onboarding flow onto a proper MVI architecture (state / intent / effect) with VM tests and Compose E2E tests, and redesigned the Onboarding screen into a 6-step 2-column grid that better explains Minus's features.

This branch fixes both problems:

• BudgetViewModel is now a thin orchestrator that delegates to 4 pure state-machine controllers - each one independently testable.
• OnboardingViewModel exposes a typed MVI contract (processIntent -> state + effects), ships with 28 unit tests, and the welcome step's "Continue" button now actually navigates to the main app.
• A new Compose E2E suite (23 tests) covers the redesigned Onboarding screen end-to-end on the emulator, including intent dispatch, effect collection, and click handling.

Change strategy

1. For the BudgetViewModel split: extract a pure state machine (no Android, no Hilt, no coroutines)
2. OnboardingUiState (data class) + sealed OnboardingUiIntent + sealed OnboardingUiEffect + enum OnboardingStep, following the same pattern as the existing BudgetMviContract and MainScreenMviContract.
3. Each E2E test instantiates OnboardingViewModel with mockk(relaxed = true) repositories and passes it to the screen. This sidesteps the @androidentrypoint requirement on the test's ComponentActivity and keeps tests focused on wiring (intent -> effect -> callback) rather than on full integration.

Implemented

• BudgetViewModel Decouple:
  • NumpadController — numpad input state (24 unit tests)
  • EditorStateController — input validation + editor state (17 unit tests)
  • TransactionActionsController — transaction lifecycle via a TransactionHandler strategy interface (11 unit tests)
  • PeriodActionsController — period actions + isFirstLaunc

Working demo

Testing

• Ran ./gradlew :app:testFossDebugUnitTest :app:connectedFossDebugAndroidTest :app:verifyPaparazziFossDebug -P android.testInstrumentationRunnerArguments.class=
• Added/updated tests when applicable
• Added screenshots or screen recordings for UI changes