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/lib/drift-scan.cjs

@@ -10,7 +10,7 @@
  * root-confinement / literal-tokenizer / sanitizer implementation instead of
  * each copying it verbatim — the exact generative-fix-divergence class this
  * epic exists to remove, now applied to the guards themselves (see
- * `.gsd/phase/refactor-3184-milestone-window-single-owner/40-design.md`,
+ * `.msd/phase/refactor-3184-milestone-window-single-owner/40-design.md`,
  * "Rejected: let the new drift guard copy Phase 1's tree-walk /
  * root-confinement / sanitizer").
  *