chore: point MSD at git.golem15.com/golem15/msd-core

The fork lives on the golem15 Gitea forge, not GitHub. Package identity now
parses either host and derives in-place raw URLs for Gitea; the identity-drift
lint accepts the new host; README drops GitHub-only badges and the npm
quickstart in favour of the checkout installer.

scripts/sync-rulesets.sh

@@ -1,7 +1,7 @@
 #!/usr/bin/env bash
 set -euo pipefail
 
-REPO="${REPO:-golem15com/msd-core}"
+REPO="${REPO:-golem15/msd-core}"
 ENFORCEMENT="${ENFORCEMENT:-evaluate}"
 
 case "$ENFORCEMENT" in