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.

tests/changeset-serialize.test.cjs

@@ -1,5 +1,5 @@
 'use strict';
-process.env.GSD_TEST_MODE = '1';
+process.env.MSD_TEST_MODE = '1';
 
 const { test, describe } = require('node:test');
 const assert = require('node:assert/strict');
@@ -198,7 +198,7 @@ describe('changeset serialize: shipped CHANGELOG citation integrity (#2359)', ()
   // entry and silently corrupts the Cline one. The Cline assertion below is the
   // guard for exactly that, and is expected to pass both before and after.
   const CHANGELOG = fs.readFileSync(path.join(__dirname, '..', 'CHANGELOG.md'), 'utf8');
-  const CURSOR_MARKER = /`\.cursor\/commands\/gsd-<name>\.md`/;
+  const CURSOR_MARKER = /`\.cursor\/commands\/gsd-<name>\.md`/; // CHANGELOG.md is unswept history
   const CLINE_MARKER = /Elevate the Cline runtime to hook parity/;
 
   function bulletsOf(version) {