refactor: improve toast apis and internals

[ovitrif]

This PR refactors the toast system to improve architecture, naming, testability, and localization.

Description

Architecture Changes

1. Replaces ToastEventBus singleton with injectable Toaster that emits events via SharedFlow
2. Adds ToastText sealed interface for type-safe toast messages (string resource vs raw string)
3. Moves ToastType enum to top-level
4. Migrates all ViewModels and Repositories to use the new Toaster via dependency injection

API Improvements

5. Renames description parameter to body across all toast APIs
6. Renames visibilityTime: Long to duration: Duration using Kotlin's type-safe Duration API
7. Removes Context dependency from Toaster - string resolution happens in ToastContent composable
8. Exposes Toaster via CompositionLocal for direct access in composables
9. Renames warning() → warn() for consistency

API Prettification

10. Adds ToastText() factory constructors via companion object invoke operators
11. Renames titleRes/bodyRes → title/body in @stringres overloads (cleaner API)
12. Removes redundant @Stable annotations from ToastType enum and value classes (inferred by Compose)

Localization & @stringres Support

13. Adds @StringRes overloads to Toaster (type-safe string resource IDs)
14. Adds ToastText overloads for mixed resource/literal cases
15. Adds ToastText.asString() composable extension using stringResource()
16. Refactors all composables to use @StringRes overloads (fixes LocalContext lint warnings)
17. Refactors all ViewModels to use @StringRes overloads
18. Localizes remaining hardcoded toast strings (UTXO load error, migration error, generic error)

Internal Refactoring

19. Renames ToastQueueManager to ToastQueue and refactors it to inherit from BaseCoroutineScope
20. Renames ToastView to ToastContent (private) and ToastOverlay to ToastHost (public API)

Documentation & Testing

21. Adds coding rule to CLAUDE.md to avoid *Manager class naming anti-pattern
22. Adds comprehensive unit tests for ToastQueue behavior (9 test cases)

API Examples

// @StringRes overloads - clean parameter names
toaster.success(title = R.string.success_title, body = R.string.success_body)
toaster.error(title = R.string.error_title)
toaster.warn(title = R.string.warning_title)

// String literal overloads
toaster.info(title = "Debug info", body = "Some details")

// ToastText overloads for mixed cases - cleaner factory
toaster.error(
    title = ToastText(R.string.error_title),
    body = ToastText(dynamicMessage),
)

Preview

N/A - Internal refactoring with no visible changes.

QA Notes

1. Toast Functionality

1. Trigger various toast types (success, error, warning, info, lightning)
2. Verify toasts appear with correct styling and dismiss properly
3. Test swipe-to-dismiss in all directions (up, left, right)
4. Verify auto-hide timer works correctly (3 second default)

2. Toast Queue Behavior

1. Trigger multiple toasts rapidly in succession
2. Verify they queue and display sequentially
3. Verify the newest toast shows immediately, replacing the current one

3. Drag Interactions

1. Start dragging a toast and verify the timer pauses
2. Release the drag and verify timer resumes with full duration

4. Localization

1. Change device language and verify toast messages appear in the correct language
2. Trigger error toasts and verify localized error messages

5. Regression Testing

• Send a payment and verify success toast appears
• Go offline and verify warning toast, then reconnect for success toast
• Copy an address to clipboard and verify info toast
• Trigger an error condition and verify error toast styling