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/4139-compact-content.md

@@ -6,7 +6,7 @@ group: Context Engineering Features
 
 **Config:** `workflow.compact_content: false`
 
-**Purpose:** Per-project opt-in to token-minimized variants of GSD's own shipped prompt
+**Purpose:** Per-project opt-in to token-minimized variants of MSD's own shipped prompt
 content — workflow instructions, planning-artifact templates, and non-Claude agent-persona
 payloads — so the always-loaded instruction window leaves more of the model's attention on
 the developer's own code (ADR-4139 Decision 2: finite attention, not per-invocation price,
@@ -30,8 +30,8 @@ it did before this feature existed.
 - REQ-COMPACT-05: An agent with no compact persona variant registered MUST fall back to its
   canonical persona and disclose the fallback inside the served payload, never fail or serve
   nothing
-- REQ-COMPACT-06: `/gsd-new-project` MUST ask the question and persist the answer;
-  `/gsd-settings` and `/gsd-config` MUST toggle it on an already-initialized project
+- REQ-COMPACT-06: `/msd-new-project` MUST ask the question and persist the answer;
+  `/msd-settings` and `/msd-config` MUST toggle it on an already-initialized project
 
 **Config:**
 | Setting | Type | Default | Description |