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.

docs/features/multi-runtime-installer-selection.md

@@ -4,7 +4,7 @@ title: Multi-Runtime Installer Selection
 group: v1.28 Features
 ---
 
-**Part of:** `npx @opengsd/gsd-core`
+**Part of:** `npx @golem15/msd-core`
 
 **Purpose:** Select multiple runtimes in a single interactive install session.
 
@@ -15,4 +15,4 @@ group: v1.28 Features
 **Process:**
 1. **Detect** — Identify available AI CLI runtimes on the system
 2. **Prompt** — Present multi-select interface for runtime selection
-3. **Install** — Configure GSD for all selected runtimes in a single session
+3. **Install** — Configure MSD for all selected runtimes in a single session