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.

src/embedding-adapter.cts

@@ -8,7 +8,7 @@
  * shape — ADR-1239 lists the wire-shape as an open question:
  *   "Exact wire-shape of the initialize handshake … Where precisely to cut the
  *    engine↔host boundary"
- * (docs/adr/1239-gsd-embeddable-orchestration-engine.md#open-questions-narrowed-by-the-research).
+ * (docs/adr/1239-msd-embeddable-orchestration-engine.md#open-questions-narrowed-by-the-research).
  * Freezing a 6-point contract before the imperative adapter exists would risk
  * rework across Phases 3-6. This slice ships only what the declarative adapter
  * (AC1) needs: the kind discriminator + runtime + install/uninstall entry.