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.

scripts/ci-rebase-check.cjs

@@ -76,7 +76,7 @@ const { fetchRef, mergeRef } = resolveBaseRefs(process.env, 'main');
 
 function main() {
   // Configure git identity (needed for merge commit).
-  runOrThrow('git', ['config', 'user.email', 'ci@gsd-redux'], 'git config user.email');
+  runOrThrow('git', ['config', 'user.email', 'ci@msd-redux'], 'git config user.email');
   runOrThrow('git', ['config', 'user.name', 'CI Rebase Check'], 'git config user.name');
 
   // Set authenticated remote URL.