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/workspace.md

@@ -0,0 +1,53 @@
+---
+name: msd:workspace
+description: Manage MSD workspaces — create, list, or remove isolated workspace environments
+argument-hint: "[--new | --list | --remove] [name]"
+allowed-tools:
+  - Read
+  - Write
+  - Bash
+  - Grep
+  - AskUserQuestion
+---
+
+<objective>
+Manage MSD workspaces with a single consolidated command.
+
+Mode routing:
+- **--new**: Create an isolated workspace with repo copies and independent .planning/ → new-workspace workflow
+- **--list**: List active MSD workspaces and their status → list-workspaces workflow
+- **--remove**: Remove a MSD workspace and clean up worktrees → remove-workspace workflow
+</objective>
+
+<routing>
+
+| Flag | Action | Workflow |
+|------|--------|----------|
+| --new | Create workspace with worktree/clone strategy | new-workspace |
+| --list | Scan ~/msd-workspaces/, show summary table | list-workspaces |
+| --remove | Confirm and remove workspace directory | remove-workspace |
+
+</routing>
+
+<execution_context>
+@~/.claude/msd-core/workflows/new-workspace.md
+@~/.claude/msd-core/workflows/list-workspaces.md
+@~/.claude/msd-core/workflows/remove-workspace.md
+@~/.claude/msd-core/references/ui-brand.md
+</execution_context>
+
+<context>
+Arguments: $ARGUMENTS
+
+Parse the first token of $ARGUMENTS:
+- If it is `--new`: strip the flag, pass remainder (--name, --repos, --path, --strategy, --branch, --auto flags) to new-workspace workflow
+- If it is `--list`: execute list-workspaces workflow (no argument needed)
+- If it is `--remove`: strip the flag, pass remainder (workspace-name) to remove-workspace workflow
+- Otherwise (no flag): show usage — one of --new, --list, or --remove is required
+</context>
+
+<process>
+1. Parse the leading flag from $ARGUMENTS.
+2. Load and execute the appropriate workflow end-to-end based on the routing table above.
+3. Preserve all workflow gates from the target workflow (validation, approvals, commits, routing).
+</process>