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/safe-undo.md

@@ -4,13 +4,13 @@ title: Safe Undo
 group: v1.34.0 Features
 ---
 
-**Command:** `/gsd-undo --last N | --phase NN | --plan NN-MM`
+**Command:** `/msd-undo --last N | --phase NN | --plan NN-MM`
 
-**Purpose:** Roll back GSD phase or plan commits safely using the phase manifest and git log, with dependency checks and a hard confirmation gate before any revert is applied.
+**Purpose:** Roll back MSD phase or plan commits safely using the phase manifest and git log, with dependency checks and a hard confirmation gate before any revert is applied.
 
 **Requirements:**
 - REQ-UNDO-01: `--phase` mode MUST identify all commits for the phase via manifest and git log fallback
 - REQ-UNDO-02: `--plan` mode MUST identify all commits for a specific plan
-- REQ-UNDO-03: `--last N` mode MUST display recent GSD commits for interactive selection
+- REQ-UNDO-03: `--last N` mode MUST display recent MSD commits for interactive selection
 - REQ-UNDO-04: System MUST check for dependent phases/plans before reverting
 - REQ-UNDO-05: A confirmation gate MUST be shown before any git revert is executed