iOS: run the zoom cover transition for modal present/dismiss

[artemlitch]

The Bookwise reader could not be presented over the bookstore pageSheet with the cover-zoom flight. The sheet had to be dismissed first, so the zoom had nothing to fly out of and nothing to land back on. This branch lets the reader present over a live sheet using the same RNSScreenStackAnimator the stack push/pop already uses.

Consumed by readwiseio/rekindled#11083.

1. The zoom animator runs for modal present/dismiss

RNSScreenStackView becomes the transitioningDelegate for modal screens whose stackAnimation is zoom, reusing the existing animator through animationControllerForPresentedController: / animationControllerForDismissedController:.

An animator.modalTransition flag guards the places where the stack's pop-side behaviour is wrong for a modal. The presenting view never left the window, so reparenting it into the transition container, or writing its frame, would orphan a still-live sheet after the transition.

2. Zoom rects are re-anchored by the card's hosting screen

Fabric's measureInWindow sums shadow-tree layout, which does not account for the native pageSheet offset, so every rect measured inside a presented sheet was short by exactly that amount. Measured on device: the card's true rect was y=114 while JS reported y=52, a 62pt gap.

That produced two visible symptoms. The stand-in composite was truncated, cut off roughly 40% down, because the card render was mapped against a slot rect that did not match the wrapper. And the whole flight landed 62pt above the real card.

RNSZoomCorrectSourceRectForCard offsets the incoming rect by the card-hosting RNSScreenView's true window origin. Stack screens sit at (0,0), so this is an exact no-op for the shipped shelf zoom. Only sheet-hosted cards are corrected.

3. The modal dismissal is the same interactive transition as the stack pop

This started out as a separate implementation: a hand-driven pose, a hand-installed dim, and a plain non-interactive dismissal on commit. It ran with no UIKit transition until release. That had a consequence beyond the animation. A screen with no transition never reports one, so transitionStart and transitionEnd never fired, and the JS that suppresses UI during a dismissal (the session recap sheet, the loading-cover reveal) never engaged. The recap sheet presented on top of an in-progress drag.

The reason for the separate path was real but the conclusion was wrong. Scrubbing a percent-driven transition parks the container's layer clock (speed=0, scrubbed timeOffset), and animations added while it is parked do not play. For a nav pop the clock restarts at finishInteractiveTransition, before the commit flight's animations commit, so the flight plays. For an over-full-screen modal it stays parked until completeTransition:, which the flight itself only calls once it lands. The flight waits for the clock and the clock waits for the flight, which is the ~400ms hold followed by a hard cut.

So restart the clock at release (RNSZoomRestartLayerClock) and let the modal use RNSPercentDrivenInteractiveTransition exactly as the stack pop does. The drag pose is still applied by hand through model writes, which render fine on a parked layer; that part was always shared between the two paths.

handleZoomSwipe: is now identical for both paths. Only the call that starts the dismissal differs, dismissViewControllerAnimated: instead of popViewControllerAnimated:. Removed: beginManualZoomDragOnView:, cancelManualZoomDrag, _zoomManualDim, _modalZoomDragAnimator, the dim handover, and the modal commit branch in animateZoomPopWithContext:. Net 201 lines deleted.

Scope

Nav-stack push/pop is untouched. Every change is gated behind modalTransition or a presented-modal check, so the shipped shelf zoom behaves identically. iOS only; no JS API changes.

android/settings.gradle is restored. An earlier commit deleted it to work around Gradle treating the fork as a separate included build when consumed via link:/file:. Consumed as a tarball, which is how it ships, its presence is harmless.

Testing

iPhone 17 Pro, Bookwise, from a recording rather than stills. Open from the modal cover, commit dismissal by drag, commit by flick, and a cancelled drag. Mid-drag frames show the reader shrunk and translated with the sheet live underneath and no recap sheet present, which was the regression. The close flight shows three distinct intermediate poses before landing, so it plays rather than snapping. The cover lands back on the sheet at full size.

Android: :app:assembleDebug is green with settings.gradle restored, installed and run on a Pixel 7 Pro (API 34). Opening a book from the bookstore modal keeps the sheet mounted, and back returns to it.