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/host-runtime-detection.cts

@@ -3,11 +3,11 @@
  *
  * `init`'s reported `agent_runtime` was hardcoding `claude` even when run
  * inside a Codex session, because resolveRuntime's ladder only checks the
- * explicit `GSD_RUNTIME` env var and `.planning/config.json`'s `runtime`
+ * explicit `MSD_RUNTIME` env var and `.planning/config.json`'s `runtime`
  * field — there was no fallback that looked at the actual host process.
  *
  * This module adds a host-detection rung strictly BELOW those two explicit
- * sources: it only runs when neither `GSD_RUNTIME` nor config `runtime` is
+ * sources: it only runs when neither `MSD_RUNTIME` nor config `runtime` is
  * set. It never writes anything (#2297 — no shared-defaults poisoning: this
  * module never touches .planning/config.json or any other file). It never
  * shells out, so there is no subprocess to time-bound — detection is pure
@@ -79,7 +79,7 @@ const NO_DETECTION: HostRuntimeDetection = { runtime: null, source: 'none', sign
 
 /**
  * Detect the host runtime from process environment signals, without ever
- * consulting the explicit GSD_RUNTIME/config.json sources (those are a
+ * consulting the explicit MSD_RUNTIME/config.json sources (those are a
  * higher-priority rung handled by resolveExplicitRuntime).
  *
  * Never throws: the whole body — including the raw `env[key]` reads, which a