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/contributing/adding-a-portability-rule.md

@@ -1,6 +1,6 @@
 # Adding a cross-platform portability lint rule
 
-GSD must run correctly on Windows as well as macOS/Linux. The `DEFECT.WINDOWS-*`
+MSD must run correctly on Windows as well as macOS/Linux. The `DEFECT.WINDOWS-*`
 taxonomy in [`CONTEXT.md`](../../CONTEXT.md) names the recurring failure shapes; a family of
 AST-based ESLint rules (the `local/*` plugin) enforces them **at write-time (in your editor)
 and in CI**, so a Windows-only defect is caught before it ships — not after it reaches the