refactor: hard-fork GSD -> MSD (Make Software Done)

Mechanical rename produced by scripts/msd-rename.cjs: gsd/Gsd/GSD -> msd/Msd/MSD
across contents and paths, upstream package/repo coordinates -> @golem15/msd-core
and golem15com/msd-core. Deep links into upstream history, sibling upstream
packages, the GSD-2 import feature, CHANGELOG.md and .changeset/ are kept as-is.

Hand edits on top: MSD block-letter banner and logos, LICENSE copyright line,
package/plugin identity, regenerated lockfile, install-tree fixtures, derived
registries and benchmark baseline; migration checksum baseline re-locked
(MSD keeps its own install state, so no install had applied the old sums);
sort-order and regex-escaped expectations in tests adjusted.

tests/hardcoded-paths.test.cjs

@@ -44,7 +44,7 @@ function collectSourceFiles(dir) {
 }
 
 // Scan source dirs only — exclude tests/ which may contain intentional fixtures
-const sourceDirs = ['bin', 'scripts', 'hooks', path.join('gsd-core', 'bin')].map(
+const sourceDirs = ['bin', 'scripts', 'hooks', path.join('msd-core', 'bin')].map(
   d => path.join(repoRoot, d)
 );
 const sourceFiles = sourceDirs.flatMap(collectSourceFiles);