fix: resolve state management issues and memory leaks

[hobostay]

Summary

This PR fixes several issues in the core state management that could cause bugs and memory leaks:

1. Fix deleteNodesAction recursive call issue

Problem: In packages/core/src/store/actions/node-actions.ts, the deleteNodesAction recursively called get().deleteNodes() inside the set() callback. This could cause state inconsistencies because the recursive call would try to modify state that's already being modified.

Fix: Now collects all descendant IDs first in a separate pass using a helper function collectDescendants(), then deletes them all in a single batch operation.

2. Fix memory leak in use-scene temporal tracking

Problem: In packages/core/src/store/use-scene.ts, the module-level variables prevPastLength, prevFutureLength, and prevNodesSnapshot persisted across store re-creations and scene unloads. This could cause memory leaks by holding references to deleted nodes.

Fix:

• These variables are now cleared in unloadScene() to release stale node references
• Added a new clearTemporalTracking() helper function for clarity
• clearSceneHistory() now calls this helper

3. Remove unused variable in wall-system

Problem: In packages/core/src/systems/wall/wall-system.tsx, the variable useFrameNb was declared and incremented but never used. This appeared to be debug code that was left in.

Fix: Removed the unused variable declaration and increment.

4. Fix requestAnimationFrame in updateNodesAction

Problem: In packages/core/src/store/actions/node-actions.ts, updateNodesAction used requestAnimationFrame without any cleanup mechanism. If updates happened rapidly, multiple RAF callbacks could be queued, causing unnecessary re-renders and potential performance issues.

Fix:

• Added module-level tracking for pending RAF (pendingRafId) and pending updates (pendingUpdates)
• Previous RAF is now cancelled before scheduling a new one
• All pending updates are batched into a single RAF callback

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Test plan

• Code compiles without errors
• No TypeScript errors introduced
• Manual testing: Scene unload/reload works correctly
• Manual testing: Node deletion with children works correctly
• Manual testing: Rapid node updates don't cause performance issues

Checklist

• Tests pass locally
• Documentation updated (n/a - no docs need updating)
• PR description clearly explains the changes

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