Fix clear map state reset

[JeremyZeng77]

Summary

• reset in-memory rotation and shape maps when clearing the terrain
• wait for undo/redo and terrain database cleanup before leaving the clear-map flow
• keep pending-change and save timestamps synchronized after the clear completes

Addresses part of #19: ghost / leftover blocks after clearing the map.

Verification

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

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 is blocked by team deployment authorization, not by a build failure in this patch.