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.

commands/msd/thread.md

@@ -0,0 +1,25 @@
+---
+name: msd:thread
+description: Manage persistent context threads for cross-session work
+argument-hint: "[list [--open | --resolved] | close <slug> | status <slug> | name | description]"
+allowed-tools:
+  - Read
+  - Write
+  - Bash
+  - Grep
+requires: [phase]
+---
+
+<objective>
+Create, list, close, or resume persistent context threads. Threads are lightweight
+cross-session knowledge stores for work that spans multiple sessions but
+doesn't belong to any specific phase.
+</objective>
+
+<execution_context>
+@~/.claude/msd-core/workflows/thread.md
+</execution_context>
+
+<process>
+Execute end-to-end.
+</process>