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/workflow-size.cjs

@@ -17,7 +17,7 @@
 const fs = require('fs');
 const path = require('path');
 
-const WORKFLOWS_DIR = path.join(__dirname, '..', 'gsd-core', 'workflows');
+const WORKFLOWS_DIR = path.join(__dirname, '..', 'msd-core', 'workflows');
 
 /**
  * Byte size of a file, counted as on an LF (Unix) checkout.
@@ -61,7 +61,7 @@ function listWorkflowStems(dir = WORKFLOWS_DIR) {
 /**
  * Measure every top-level `.md` file in `dir`, keyed by filename, byte sizes.
  * Generic over directory and an optional filename predicate — used for both
- * workflows (`gsd-core/workflows/*.md`) and agents (`agents/gsd-*.md`) so the
+ * workflows (`msd-core/workflows/*.md`) and agents (`agents/msd-*.md`) so the
  * size guards and the baseline generator share one measurement path (#1074).
  * Non-recursive by design.
  *