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.

.claude-plugin/plugin.json

@@ -1,14 +1,14 @@
 {
-  "name": "gsd-core",
-  "displayName": "GSD Core",
+  "name": "msd-core",
+  "displayName": "MSD Core",
   "version": "1.14.0",
-  "description": "GSD Core is a meta-prompting, context engineering, and spec-driven development system for AI coding agents.",
+  "description": "MSD Core is a meta-prompting, context engineering, and spec-driven development system for AI coding agents.",
   "author": {
-    "name": "open-gsd",
-    "url": "https://github.com/open-gsd"
+    "name": "golem15com",
+    "url": "https://github.com/golem15com"
   },
-  "homepage": "https://github.com/open-gsd/gsd-core",
-  "repository": "https://github.com/open-gsd/gsd-core",
+  "homepage": "https://github.com/golem15com/msd-core",
+  "repository": "https://github.com/golem15com/msd-core",
   "license": "MIT",
   "keywords": [
     "spec-driven-development",
@@ -16,8 +16,8 @@
     "workflow",
     "context-engineering",
     "claude-code",
-    "gsd"
+    "msd"
   ],
-  "commands": "./commands/gsd/",
+  "commands": "./commands/msd/",
   "skills": "./skills/"
 }