fix(android-legacy): refresh the VMI snapshot eagerly when binding changes

The snapshot getter's posted-refresh design broke the read-after-bind
contract: autoplay-false-trigger's issue #156 guard binds via the
dataBind prop and does a one-shot getViewModelInstance() read, which
returned the stale (null) snapshot on android-legacy (iOS still reads
synchronously). Binding always happens on the main thread, so refresh
the snapshot right where it changes (bindViewModelInstance and
bindToStateMachine) — a JS read after binding then sees a fresh value
with no blocking and no polling needed.

Author: mfazekas

android/src/legacy/java/com/rive/RiveReactNativeView.kt

@@ -165,6 +165,10 @@ class RiveReactNativeView(context: ThemedReactContext) : FrameLayout(context) {
     if (!stateMachines.isNullOrEmpty()) {
       stateMachines.first().viewModelInstance = vmi
     }
+    // Keep the snapshot fresh at the moment binding changes so a JS-side
+    // read right after binding sees the instance without waiting for a
+    // posted refresh (guards the read-after-bind contract, issue #156).
+    lastKnownViewModelInstance = readViewModelInstanceOnMain()
   }
 
   // Cache maintained on the main thread: the controller's state-machine list
@@ -381,6 +385,9 @@ class RiveReactNativeView(context: ThemedReactContext) : FrameLayout(context) {
         }
       }
     }
+    // Keep the snapshot fresh at the moment binding changes — see
+    // lastKnownViewModelInstance.
+    lastKnownViewModelInstance = readViewModelInstanceOnMain()
   }
 
   private fun convertEventProperties(properties: Map<String, Any>?): Map<String, EventPropertiesOutput>? {