Catch-all commit for outstanding pre-existing local changes. Mixes
several themes that would normally be split:
- Rename: UxPlugin → XPlugin across iOS, macOS, Android registrants.
- New top-level packages under lib/src/: anim/ (animated values,
panes, sheets, dock, measured), core/ (Emitter, ReactiveBuilder
scaffolding, presenter/widget/value/dispose primitives), navi/
(Screen/ScreenStack/Router/hero/transitions), reactive/.
- Edits across existing plugins (clipboard, crash, file, gallery,
keyboard, scanner, sensor, url) to align with the new core.
- Test updates and CHANGELOG/README touches accompanying the above.
Flutter's Clipboard API only exposes text shapes. Banlu's chat composer
needs image bytes from the system clipboard for desktop paste, so add
a UxClipboard facade backed by per-platform native plugins:
* iOS: prefer raw PNG/JPEG bytes off the pasteboard, fall back to
re-encoding `UIPasteboard.image` as PNG.
* macOS: prefer NSPasteboard `.png`, fall back to TIFF transcoded
through NSBitmapImageRep so screenshots / Preview hand-offs still
work.
* Android: read primary ClipData's first item URI and stream the bytes
through ContentResolver — don't trust the clip description's MIME,
copy whatever the resolver returns.
Returns null (never throws) when the clipboard has no image — callers
treat null as "fall through to text paste".
