Docs: hygiene sweep — stale/misattributed doc-comments + CLAUDE.md example

- Repoint CLAUDE.md testing example from the deleted HeartbeatSystemTests to HealthApplyDamageSystemTests.
- Stale deleted-system refs: ResourceFieldSpawner/ClutterFieldSpawner(+Authoring) now cite RoomFieldSystem (was ExpeditionFieldSystem); BuildPlaceRequest drops the deleted RegionTransitRequest from its 'mirrors' list.
- Stale package version: 'Netcode 1.13.2' -> 'Netcode 1.x' in ProjectileClassificationSystem + BuildPlaceRequest.
- WorldCollisionComponents: remove the duplicated EnvironmentMask summary line; FeelConfig: fix the mangled 'is hitmap)' sentence.

Comment/doc only; compiles clean.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Assets/_Project/Scripts/Client/Combat/ProjectileClassificationSystem.cs

@@ -28,7 +28,7 @@ namespace ProjectM.Client
     [CreateAfter(typeof(GhostReceiveSystem))]
     // NOTE: intentionally NOT [BurstCompile]d. The cross-assembly generic
     // SnapshotDataBufferComponentLookup.TryGetComponentDataFromSnapshotHistory<T>() trips a Burst
-    // internal compiler error (type-hash resolution) on Netcode 1.13.2. Classification only runs when
+    // internal compiler error (type-hash resolution) on Netcode 1.x (installed: 6.5.0). Classification only runs when
     // ghost spawns are received (a cold path, not the prediction loop), so a managed job is fine here.
     public partial struct ProjectileClassificationSystem : ISystem
     {