Scene authoring: ConversionStatue prefab, registration and wiring

- ConversionStatue.prefab: Hider variant stripped of player-only components
  (NetworkPlayerSetup, PlayerAnimationSync, ConcealmentMeter, PlayerScaler),
  controllers disabled, MatchStatue added.
- DefaultNetworkPrefabs.asset: register the statue prefab.
- Main.unity: wire MatchManager.statuePrefab.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Assets/Prefabs/ConversionStatue.prefab.meta

@@ -0,0 +1,7 @@
+fileFormatVersion: 2
+guid: 883d1d5c434f5a44884d1ef38a3a5db5
+PrefabImporter:
+  externalObjects: {}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: