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/runtime-artifact-install-plan.cts

@@ -83,7 +83,7 @@ interface ComputePathPrefixOpts {
    *  include style is opted in on a local install. Optional — an omitted value
    *  falls back to the absolute prefix, which is the pre-#4377 behavior. */
   localDirName?: string;
-  /** #4377: explicit opt-in override. Defaults to `GSD_RELATIVE_INCLUDES === '1'`
+  /** #4377: explicit opt-in override. Defaults to `MSD_RELATIVE_INCLUDES === '1'`
    *  inside `_computePathPrefix`; present here so tests can drive both arms
    *  without mutating the environment. */
   projectRelative?: boolean;