[Xamarin.AndroidX.Compose.Runtime] Stop stripping the whole package; ship real bindings

[jonathanpeppers]

The Xamarin.AndroidX.Compose.Runtime NuGet currently ships an empty managed facade. Its Transforms/Metadata.xml carries:

<remove-node path="/api/package" />

with a comment that Compose is Kotlin-only and "does not make sense for C# until parsing of kotlin and transpiling to c# is ready (if ever)".

That's too pessimistic — for the runtime types specifically, the binding generator does fine on the AAR if you add a small, bounded set of targeted <remove-node> entries. I have a proven-working rebinding of androidx.compose.runtime:runtime-android 1.9.4 in ComposeNet.Bindings.Runtime — it builds, packs, and is consumed end-to-end by a working Compose-from-C# sample app.

Requested change

1. Delete <remove-node path="/api/package" /> from the recipe's Transforms/Metadata.xml.
2. Port the 14 targeted <remove-node> entries from the proven-working Transforms/Metadata.xml. They cover:
   • SnapshotStateList/Map/Set + their *Kt companions (KMP collection-jvm interface erasure ⇒ Size()/Values()/EntrySet() signature mismatch with java.util.*).
   • MutableSnapshot / Snapshot.getReadObserver (Kotlin typealias (Any) -> Unit).
   • AbstractApplier<T> (abstract IApplier.insertBottomUp/TopDown(int, T) doesn't satisfy IApplier<Object> after erasure).
   • BroadcastFrameClock, PausableMonotonicFrameClock (missing CoroutineContext.Element.key override).
   • MutableIntState/LongState/FloatState/DoubleState and their non-mutable peers (primitive value accessor hides MutableState<T>.value setter).
   • MonotonicFrameClock.Key and SnapshotContextElement.Key (nested companion Key clashes with inherited CoroutineContext.Element.key).
   • ComposerKt.isAfterFirstChild (two inline-class overloads collapse to identical JVM signatures).
3. Add <AndroidIgnoredJavaDependency Include="androidx.collection:collection-jvm:1.5.0" /> to satisfy the dependency verifier (the -android variant from Xamarin.AndroidX.Collection already satisfies it at runtime).
4. Regenerate api/PublicApi*.txt. The reversal from "no public API" to "real bindings" adds many hundreds of public types/members; the existing baselines will fail the API compatibility check until refreshed.

Why now

Google declared Compose-first in May 2026 — android.widget.*, Fragments, RecyclerView, ViewPager are now maintenance mode. .NET for Android needs a story for hosting Compose UI from C#, and the empty-facade policy is the only thing blocking it for the runtime types. See https://github.com/jonathanpeppers/compose-net (notably NOTES.md and README.md) for the broader strategy.

Sequencing

This is the prerequisite for two companion issues (UI/Foundation/Foundation.Layout and Material3) — Runtime ships first because every other Compose recipe references real types from it.