Add project docs

[MarcHidalgo5]

Summary

Adds a project documentation directory for BSWInterfaceKit with package context, module map, platform support notes, feature notes, ADRs, and technical pending items.

Adds repository agent instructions for keeping Docs/ updated when public UI APIs, SwiftUI/UIKit behavior, Android Skip behavior, view-model lifetime, async loading/error handling, navigation, media/social integrations, styling, snapshots, or pending work changes.

[michele-theleftbit]

This pull request looks great. Given the current Sources/BSWInterfaceKit structure, what do you think about using this opportunity to reorganize the folders?

SwiftUI is already isolated, while most of the remaining folders (Cells, CollectionViewLayout, ViewControllers, Views, etc.) are UIKit-oriented. Grouping UIKit-specific code under a dedicated UIKit/ directory, while keeping SwiftUI/ separate, would make UIKit dependencies easier to identify and provide a clearer path for progressively deprecating legacy UIKit APIs in a more controlled way.

[MarcHidalgo5]

Yes, that makes sense, we can take advantage of this PR so we can keep the Docs synchronized with the new structure