refactor(tests): consolidate Worktree Module — 13 files → 3 (#3752)

* refactor(tests): consolidate Worktree Module — 13 files → 2

Closes #3742

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* fix(changeset): correct frontmatter format for 3742 fragment

type:/pr: fields required by docs-lint; replaces @changesets/cli
package-bump format with the repo's custom fragment schema.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* refactor(tests): split consolidated worktree.test.cjs along cleanup seam (≤ 800 LOC/file)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* chore(changeset): update 3742 fragment — 13→3 files, ≤800 LOC/file

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* chore(changeset): fix pr reference 3738→3752 in 3742 fragment

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

.changeset/3742-consolidate-worktree-tests.md

@@ -0,0 +1,14 @@
+---
+type: Changed
+pr: 3752
+---
+<!-- docs-exempt: internal test refactor only — no user-facing surface changed -->
+
+Consolidates the Worktree Module test cluster from 13 files to 3, satisfying the lint-test-file-count allowlist ceiling.
+
+- Merged 11 bug-fix CJS test files into `tests/worktree.test.cjs` (branch-check/workspace-safety) and `tests/worktree-cleanup.test.cjs` (HEAD-attachment/cleanup, split along cleanup seam, each ≤ 800 LOC)
+- Retained `tests/worktree-safety.test.cjs` with safety policy tests merged in
+- No `worktree` entry needed in allowlist (3 files ≤ 4 cluster budget)
+- Added Worktree Workstream Seam Module glossary entry to `CONTEXT.md`
+
+Closes #3742