implement initial demo with vitest and react-testing-library

[frankpereiragomez]

• [x] import initial code
• [x] test PokemonCard component first version (without refactor)
• [x] test PokemonDetails page first version (without refactor)
• [x] test PokemonList component first version (without refactor)
• [x] refactor components using custom hooks
• [x] test custom hooks
• [x] refactor service logic abstracted from component
• [x] refactor router
• [x] create custom errors classes
• [x] fix error handling in the business logic
• [x] create 404 not found page