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/changeset/lint.cjs

@@ -31,7 +31,7 @@ const OPT_OUT_LABEL = 'no-changelog';
 // fragment or an explicit opt-out label. Test/CI/docs/lock files do not.
 const USER_FACING_PREFIXES = [
   'bin/',
-  'gsd-core/',
+  'msd-core/',
   'src/',
   'agents/',
   'commands/',