Prune stale terrain transform data

[JeremyZeng77]

Summary

• prune rotation and shape maps to the new terrain positions whenever toolbar/import flows replace the terrain wholesale
• persist the pruned rotation/shape stores together with the new terrain data
• prevent stale transform records from surviving imports, generated terrain, or other full-map replacements

Addresses part of #19: ghost / leftover terrain state after map replacement.

Verification

• git diff --check
• npm run build passes; build reports existing source-map, lint, and bundle-size warnings unrelated to this terrain transform pruning.

Bounty / payment

• PayPal: https://paypal.me/Jeremytsangchina
• Backup USDT TRC20: TWupTAoFjxR2VmqUUvzhfmUwXVZR6Kvz1Y

[vercel]

Someone is attempting to deploy a commit to the Hytopia Team on Vercel.

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[JeremyZeng77]

Verification note: local
pm run build\ passes for this branch. The visible Vercel status, if present, is blocked by Hytopia team deployment authorization rather than by this patch.