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.

docs/features/installer-migrations.md

@@ -10,7 +10,7 @@ group: v1.42.1 Features
 - First-time baseline migration records managed files.
 - Legacy stale-file cleanup uses ownership evidence before deleting or rewriting.
 - User-owned artifacts are preserved.
-- Ambiguous GSD-looking files block with a clear report instead of being silently overwritten.
+- Ambiguous MSD-looking files block with a clear report instead of being silently overwritten.
 - Migration plans support dry-run reporting and rollback protection.
 
 **Requirements:**