PixDala alpha.39 released and verified

This archive contains the alpha.39 implementation candidate based on the verified alpha.38 source checkpoint and subsequent documentation update.

Changes: Desktop completion-overlay stacking, viewer-specific completion message, remote destruction particle propagation, and version/cache-busting updates.

Lifecycle constraint: the server remains authoritative. The destroyer starts `destroying`, other open clients observe that transition through revision polling and animate locally, and only the destroyer completes the server-side reset.

Local automated verification: `npm run check` -> structure OK, JavaScript syntax OK, 10 unit, 17 integration, 8 API; total 35/35.

Manual QA passed in Telegram on Mobile and Desktop with multiple users: viewer-specific completion UI for a different Telegram user, Desktop stacking, remote particle animation, reset synchronization, and cross-viewer occupation audio. Final-participant completion flow was also verified during the release QA.

Do not deploy this patch by copying files directly to the VPS. Replace the corresponding files in the Windows repository, run `npm.cmd run check`, review Git diff, commit/push/tag through the normal Git workflow, then deploy with `scripts/deploy-test.sh <tag>`.