Component: Connected inputs

Choosing an option shows/hides other options, like how car websites let you choose a make, which shows a list of models for that vendor, which then shows a list of years.

No file, entry point, or test is named. Start by locating the existing input and component implementation, then clarify the supported connected-input behavior using the make/model/year example. Done means dependent selections can reveal the next available options in the described sequence, with the behavior covered by tests if the project has them.

Written by the indexing model from the issue text.