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/thread-session-management.test.cjs

@@ -10,7 +10,7 @@ const path = require('path');
 
 describe('thread session management (#2156)', () => {
   const threadCmd = fs.readFileSync(
-    path.join(__dirname, '..', 'gsd-core', 'workflows', 'thread.md'),
+    path.join(__dirname, '..', 'msd-core', 'workflows', 'thread.md'),
     'utf8'
   );