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.

capabilities/pattern-mapper/fragments/plan-pre.md

@@ -4,7 +4,7 @@
 **Padded phase:** {padded_phase}
 
 <required_reading>
-- {context_path} (USER DECISIONS from /gsd:discuss-phase)
+- {context_path} (USER DECISIONS from /msd:discuss-phase)
 - {research_path} (Technical Research)
 </required_reading>