fix: use druid 0.1.247 runtime images

[MarcStdt]

Summary

• bump scroll runtime pins and workflow druid pins to v0.1.247
• use v0.1.247-steamcmd for Steam/LGSM/Rust runtime and prebuild paths
• remove the stale CS2 postinstall template from LGSM build metadata so regeneration keeps the concrete postinstall plus permission patch chunks

Validation

• docker run --rm --platform linux/amd64 --entrypoint sh artifacts.druid.gg/druid-team/druid:v0.1.247-steamcmd -lc "test -s /home/druid/.steam/sdk64/steamclient.so; test -s /home/druid/.steam/sdk32/steamclient.so"
• make build-tree
• ./scripts/validate_all_scrolls.sh
• go run ./scripts/validate-scrolls.go
• git diff --check
• rg --hidden -n "v0\.1\.246|postinstall-template|postinstall\.sh\.scroll_template" . returned no matches

[druid-infra]

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