Refactor ViewModelFactory to use DSL

[marcellogalhardo]

Change TodoViewModelFactory to use the viewModelFactory DSL. This replaces manual class checks and unchecked casts.

[gemini-code-assist]

Code Review

This pull request refactors the TodoViewModelFactory to use the viewModelFactory DSL and initializer blocks, simplifying the ViewModel creation logic. A review comment suggests refining the error handling in the CreationExtras.application extension property to provide more specific error messages when the application key is missing versus when there is a type mismatch.

[gemini-code-assist]

The error message in the application extension property is slightly misleading. If APPLICATION_KEY is present but the value is not a TodoApplication (e.g., during testing with a mock application), the current message still claims the key must be present. Consider refining the error handling to distinguish between a missing key and a type mismatch for better debugging.

Suggested change

	private val CreationExtras.application: TodoApplication
	get() = this[APPLICATION_KEY] as? TodoApplication
	?: error("'CreationExtras' must contain 'APPLICATION_KEY' to access 'TodoApplication'")
	private val CreationExtras.application: TodoApplication
	get() = (this[APPLICATION_KEY] ?: error("CreationExtras must contain APPLICATION_KEY"))
	.let { it as? TodoApplication ?: error("Application associated with APPLICATION_KEY must be of type TodoApplication") }