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/gen-platform-conformance-tier.cjs

@@ -260,7 +260,7 @@ const ALWAYS_REAL_OS = new Map([
 
 /**
  * macOS-specific detection categories (#4593, design doc
- * .gsd/phase/chore-4593-macos-conformance-tier/40-design.md). Built new,
+ * .msd/phase/chore-4593-macos-conformance-tier/40-design.md). Built new,
  * rather than reusing CATEGORIES above minus its Windows-specific entries,
  * because that naive exclusion barely narrows anything (measured: 546 -> 424
  * files, 78%) — most files match multiple general-tier signals simultaneously