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.

docs/features/fast-mode.md

@@ -4,7 +4,7 @@ title: Fast Mode
 group: v1.27 Features
 ---
 
-**Command:** `/gsd-fast [task description]`
+**Command:** `/msd-fast [task description]`
 
 **Purpose:** Execute trivial tasks inline without spawning subagents or generating PLAN.md files. For tasks too small to justify planning overhead: typo fixes, config changes, small refactors, forgotten commits, simple additions.
 
@@ -14,6 +14,6 @@ group: v1.27 Features
 - REQ-FAST-03: System MUST track the task in `.planning/quick/` for state consistency
 - REQ-FAST-04: System MUST NOT be used for tasks requiring research, multi-step planning, or verification
 
-**When to use vs `/gsd-quick`:**
-- `/gsd-fast` — One-sentence tasks executable in under 2 minutes (typo, config change, small addition)
-- `/gsd-quick` — Anything needing research, multi-step planning, or verification
+**When to use vs `/msd-quick`:**
+- `/msd-fast` — One-sentence tasks executable in under 2 minutes (typo, config change, small addition)
+- `/msd-quick` — Anything needing research, multi-step planning, or verification