- Replace NSColor.controlBackgroundColor with .regularMaterial
- Remove unused VisualEffectBackground and AutocompletePopupContent
- Simplify code by using native SwiftUI material modifiers
- Replace SwiftUI overlay with custom NSWindow implementation
- Use NSColor.controlBackgroundColor for opaque background
- Add proper click-outside-to-dismiss functionality
- Handle Swift concurrency and actor isolation correctly
- Inspired by SuggestionsDemo but simplified for our use case