Consider providing dedicated prompts or skills for complicated breaking change guides

It seems the [UIScene](https://docs.flutter.dev/release/breaking-changes/uiscenedelegate) and [Built-in Kotlin](https://docs.flutter.dev/release/breaking-changes/migrate-to-built-in-kotlin) breaking changes/migrations are quite complicated and keep getting more complicated with sometimes multiple additions or clarifications a week. I worry they are getting a bit hard to follow.

Can we/should we suggest developers try using agents to help them with the migrations? If so, is giving them the current guides sufficient, should we provide an optional prompt to get them started? Are the current guides we have now sufficient for agents or we create something more focused or more effective for agents?

I imagine the impact for these two cases is potentially limited now but perhaps it can be an exploration to set a pattern for complicated migrations going forward?

@jmagman @reidbaker @lamek for thoughts.

Start with the UISceneDelegate and Built-in Kotlin breaking-change guides linked in the issue, and review how their current migration steps are organized. Determine whether optional agent prompts or more focused guidance would help; done means establishing a documented, reusable approach for these complicated migrations if the exploration supports one.

Written by the indexing model from the issue text.