screen_capturer needs to support Swift package manager going forward

[mauricev]

The following plugins do not support Swift Package Manager for macos:

• screen_retriever_macos
• screen_capturer_macos
• desktop_multi_window
  This will become an error in a future version of Flutter. Please contact the plugin maintainers to request Swift Package Manager adoption.

[m13v]

the SPM migration for screen capture is more involved than most Flutter plugins because the underlying macOS APIs changed too. if you're targeting macOS 14+ you should use ScreenCaptureKit instead of CGWindowListCreateImage. might be a good time to modernize the capture backend alongside the build system migration. ScreenCaptureKit's API is honestly much cleaner for this kind of use: per-window filtering, proper frame callbacks through SCStreamDelegate, and hardware-accelerated encoding are all built in.

[m13v]

our ScreenCaptureKit implementation as reference for the migration, handles SCContentFilter setup, SCStream configuration, and frame delivery through delegate callbacks: https://github.com/m13v/macos-session-replay/blob/main/Sources/SessionReplay/ScreenCaptureService.swift