fix: prevent ComposeUiClusterRenderer crash on fast back gesture with compose-ui 1.10+

[kikoso]

Fixes #875

Summary

• DefaultClusterRenderer's MarkerModifier uses an Android Handler queue that continues processing render tasks after the Compose scope is cancelled (e.g. fast back gesture). When a new ComposeView is created at that point, it attempts composition using an already-disposed CompositionContext, triggering the crash.
• The ViewTreeLifecycleOwner fix shipped in v8.3.0 addressed the static case (no lifecycle owner on detached views) but not this dynamic teardown case.

Changes

• Add scope.isActive guard at the top of getDescriptorForCluster and onBeforeClusterItemRendered. When the coroutine scope is cancelled, these methods fall through to the default super implementation (standard Google Maps rendering) instead of creating new off-screen ComposeViews with a stale/disposed CompositionContext.
• Add ViewTreeSavedStateRegistryOwner alongside the existing ViewTreeLifecycleOwner on off-screen views, providing full compose-ui 1.10+ compatibility for cluster content that uses rememberSaveable or other saved-state APIs.

Test plan

• Navigate to a map screen with Clustering() using custom clusterContent/clusterItemContent and many markers (so MarkerModifier is still actively rendering)
• Immediately perform a fast back gesture (predictive back or physical back key)
• Confirm no crash occurs — map falls back to default cluster rendering during the transition
• Confirm normal clustering still works as expected when staying on the screen

[googlemaps-bot]

Code Coverage

Overall Project	24.82%	❌

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