Update Minecraft Vanilla scrolls for new runtime

[MarcStdt]

Summary

• convert Minecraft Vanilla generated scrolls to the new container/signal procedure format
• keep all Vanilla versions generated from the shared template
• add PR CI publishing to artifacts.druid.gg/druid-team-experimental with tag- refs

Validation

• go run generate-scrolls.go ./scrolls/minecraft/minecraft-vanilla
• make build-tree
• druid validate for every ./scrolls/minecraft/minecraft-vanilla/*/scroll.yaml
• git diff --check
• workflow YAML parse
• go test ./...

[druid-infra]

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