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/generate-package-identity.cjs

@@ -20,10 +20,24 @@
  * Parse `owner/name` out of a package.json `repository.url`, stripping the
  * `git+` prefix and `.git` suffix npm conventionally adds.
  */
-function parseRepoSlug(repository) {
+function parseRepo(repository) {
   const url = typeof repository === 'string' ? repository : (repository && repository.url) || '';
-  const m = url.replace(/^git\+/, '').replace(/\.git$/, '').match(/github\.com[/:]([^/]+\/[^/]+)$/);
-  return m ? m[1] : '';
+  const m = url.replace(/^git\+/, '').replace(/\.git$/, '').match(/(github\.com|git\.golem15\.com)[/:]([^/]+\/[^/]+)$/);
+  return m ? { host: m[1], slug: m[2] } : { host: '', slug: '' };
+}
+
+function parseRepoSlug(repository) {
+  return parseRepo(repository).slug;
+}
+
+/**
+ * Raw-file URL for CHANGELOG.md on the repo's default branch. GitHub serves raw
+ * files from a separate host; the golem15 Gitea forge serves them in-place.
+ */
+function changelogRawUrlFor(host, slug) {
+  if (!slug) return '';
+  if (host === 'github.com') return `https://raw.githubusercontent.com/${slug}/main/CHANGELOG.md`;
+  return `https://${host}/${slug}/raw/branch/next/CHANGELOG.md`;
 }
 
 /**
@@ -47,11 +61,9 @@ function slugifyPackageName(name) {
 function deriveIdentity(pkg = {}) {
   const packageName = pkg.name || '';
   const binName = pkg.bin ? Object.keys(pkg.bin)[0] || '' : '';
-  const repoSlug = parseRepoSlug(pkg.repository);
-  const repoUrl = repoSlug ? `https://github.com/${repoSlug}` : '';
-  const changelogRawUrl = repoSlug
-    ? `https://raw.githubusercontent.com/${repoSlug}/main/CHANGELOG.md`
-    : '';
+  const { host, slug: repoSlug } = parseRepo(pkg.repository);
+  const repoUrl = repoSlug ? `https://${host}/${repoSlug}` : '';
+  const changelogRawUrl = changelogRawUrlFor(host, repoSlug);
   const cacheSlug = slugifyPackageName(packageName);
   const updateCacheFileName = cacheSlug ? `msd-update-check-${cacheSlug}.json` : 'msd-update-check.json';
   return { packageName, binName, repoSlug, repoUrl, changelogRawUrl, cacheSlug, updateCacheFileName };