Render ProgressView and Toggle

[colemancda]

First half of the form controls work: ProgressView and Toggle. Stepper, Slider, TextField, and Picker follow separately.

Rebased onto master now that PureSwift/Android#45 has merged — the ProgressBar binding fix this depends on is upstream, so this no longer carries any external blocker.

ProgressView

_FractionalProgressView and _IndeterminateProgressView are the renderer hooks the default progress style already emits, so both get a primitive conformance backed by ProgressBar.

Determinate and indeterminate progress are separate widgets rather than one widget toggling setIndeterminate, because the horizontal track is only selectable through a style attribute at construction time — which is what needed the upstream binding fix, since ProgressBar had no constructors at all. Progress is reported on a fixed integer scale since ProgressBar works in whole steps while ProgressView reports a fraction.

Toggle

Rendered as a Material switch, bound to its Bool.

This is supplied as the default toggle style rather than as a primitive conformance on Toggle. A primitive conformance looks like it should work, but Toggle declares @Environment(\.toggleStyle), which is read during environment injection whether or not the body is ever evaluated — and _ToggleStyleKey traps unless the renderer supplies a default. That crashed on launch. Going through the style system fixes the crash and has the side benefit that .toggleStyle(_:) keeps working.

The checked-change callback needs a new JNI bridge, CompoundButtonOnCheckedChangeListener, following ViewOnClickListener exactly. The listener guards against writing back when the value already matches, so the reconciler setting the checked state during an update doesn't churn the binding.

Build script

build-swift.sh copied only libSwiftAndroidApp.so into jniLibs. After the upstream linking changes the app also loads libSwiftJava.so at runtime and dies on startup with UnsatisfiedLinkError without it, so the script now copies every built shared library. This is unrelated to the controls themselves but breaks any fresh build, so it is fixed here.

Verification

On the emulator, against the merged upstream bindings, via a new Controls gallery screen:

• The switch flips and drives its bound @State, with a label reflecting it.
• The indeterminate spinner animates.
• The determinate bar tracks its value across repeated updates (25% → 75%).

The gallery screen is a flat eleven-child block, which also exercises the view builder change from #11.