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.

src/drift.cts

@@ -2,7 +2,7 @@
  * Codebase Drift Detection (#2003)
  *
  * Detects structural drift between a committed codebase and the
- * `.planning/codebase/STRUCTURE.md` map produced by `gsd-codebase-mapper`.
+ * `.planning/codebase/STRUCTURE.md` map produced by `msd-codebase-mapper`.
  *
  * Four categories of drift element:
  *   - new_dir    → a newly-added file whose directory prefix does not appear
@@ -36,7 +36,7 @@
 
 import fs from 'node:fs';
 import { platformWriteSync, posixNormalize } from './shell-command-projection.cjs';
-import { formatGsdSlash } from './runtime-slash.cjs';
+import { formatMsdSlash } from './runtime-slash.cjs';
 
 // ─── Constants ───────────────────────────────────────────────────────────────
 
@@ -299,7 +299,7 @@ function buildMessage(elements: DriftElement[], affectedPaths: string[], action:
     // caller (verify.cmdVerifyCodebaseDrift) resolves the runtime once and
     // passes it in via input.runtime so emitted commands match the project
     // the caller is targeting, not the current process directory.
-    const mapCmd = formatGsdSlash('map-codebase', runtime || 'claude');
+    const mapCmd = formatMsdSlash('map-codebase', runtime || 'claude');
     lines.push(
       `Run ${String(mapCmd)} --paths ${affectedPaths.join(',')} to refresh planning context.`,
     );