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/task-content-resolution.cts

@@ -29,7 +29,7 @@
  * nothing happened.
  *
  * ADR-457 build-at-publish: source in src/task-content-resolution.cts,
- * compiled to gsd-core/bin/lib/task-content-resolution.cjs (gitignored).
+ * compiled to msd-core/bin/lib/task-content-resolution.cjs (gitignored).
  */
 
 // Use non-destructured namespace import so test-time mock.method(childProcess,
@@ -192,8 +192,8 @@ const TRACKER_PREFIX_RE = /^[a-z][a-z0-9-]*$/;
 /**
  * Split a `tracker-id` attribute value into its prefix and id, on the FIRST
  * `:` only — colons after the first stay in the id verbatim (a tracker whose
- * native ids contain colons, e.g. `beads:issue:GSD-1` → `{prefix: "beads",
- * id: "issue:GSD-1"}`).
+ * native ids contain colons, e.g. `beads:issue:MSD-1` → `{prefix: "beads",
+ * id: "issue:MSD-1"}`).
  *
  * PURE. Returns `null` for `null`/empty input, and for a string with no `:`
  * at all (nothing to split — there is no prefix to match a resolver against).