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/secret-scan.sh

@@ -17,7 +17,7 @@
 #              This flag does not change secret-detection logic — only which
 #              exclusions are applied.
 #
-# Exit codes (ADR-3889, #3908 — registered in gsd-core/bin/shared/exit-codes.json):
+# Exit codes (ADR-3889, #3908 — registered in msd-core/bin/shared/exit-codes.json):
 #   0                = clean
 #   1                = findings detected
 #   $EXIT_USAGE       (64) = usage error (bad argv, missing --file/--dir target)
@@ -47,7 +47,7 @@ set -euo pipefail
 # failure if the fragment is missing — never fall back to a guessed literal
 # integer, and never let a missing registry silently degrade to exit 0.
 SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
-EXIT_CODES_SH="$SCRIPT_DIR/../gsd-core/bin/shared/exit-codes.sh"
+EXIT_CODES_SH="$SCRIPT_DIR/../msd-core/bin/shared/exit-codes.sh"
 if [[ ! -f "$EXIT_CODES_SH" ]]; then
   echo "secret-scan: FATAL: exit-code registry not found at $EXIT_CODES_SH" >&2
   echo "  Regenerate with: node scripts/gen-exit-code-registry.cjs --write" >&2