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/explanation/interface-versioning-policy.md

@@ -1,6 +1,6 @@
 # Interface versioning and deprecation policy
 
-This explains how the GSD Host-Integration Interface (ADR-1239) evolves over
+This explains how the MSD Host-Integration Interface (ADR-1239) evolves over
 time — what is an additive change, what is breaking, how `PROTOCOL_VERSION`
 bumps, and what deprecation window host-plugin authors can rely on. The policy
 exists because a published SDK is a long-term compatibility commitment (Hyrum's