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.
Two new methods on `UxFile`, both designed to keep large file content
out of the platform-channel buffer (the failure mode of file_selector
on Android: a ~200 MB video PUT through the Pigeon codec OOM'd the
JVM via `byte[size]` allocation in `FileSelectorApiImpl`).
`UxFile.pick({mimeTypes})` returns `UxPickedFile?` with `path`, `name`,
`mimeType`, `size`. The platform channel reply carries only the
metadata; bytes never cross.
- Android: `ACTION_OPEN_DOCUMENT` + `EXTRA_MIME_TYPES`, registered
as `ActivityResultListener`. On result, stream-copies the SAF
content URI to `cacheDir/ux_pick/<ts>_<safeName>` via an 8 KB
buffer (no full-file allocation in JVM heap), returns the cache
path.
- iOS: `UIDocumentPickerViewController(documentTypes:in: .import)`
— `.import` mode copies the picked file into the app's
Documents/Inbox so the URL is stable. Strong-retained delegate
(the picker's delegate ref is weak).
- macOS: `NSOpenPanel` with `allowedFileTypes`. Sheet-modal when a
Flutter window exists; free-modal otherwise.
`UxFile.videoThumbnail({path, atMs, maxWidth})` returns
`UxVideoThumbnail?` (PNG bytes + dims).
- Android: `MediaMetadataRetriever.getFrameAtTime(..., OPTION_CLOSEST_SYNC)`,
`Bitmap.createScaledBitmap` to maxWidth, PNG-encode via
`ByteArrayOutputStream`, recycle bitmaps in `finally`, release
retriever in `finally`.
- iOS: `AVAssetImageGenerator` with `appliesPreferredTrackTransform = true`,
`maximumSize = (maxWidth, 0)` (preserve aspect), ±500 ms tolerance
for keyframe alignment, decode on `userInitiated` queue.
- macOS: same generator, encoded via `NSBitmapImageRep`.
Compatible with the package's existing iOS 13 / macOS 10.15 deployment
targets — uses legacy `kUTType*` + `UTTypeCreatePreferredIdentifierForTag`
instead of `UTType` (iOS 14 / macOS 11).
