fix: Windows-native CI findings on latest master

Local run of check:ci:windows-complete (the windows-native gate) on
latest master surfaced five Windows-only failures, all unreachable by
current CI because the native windows job is disabled and the wine gate
only covers build+site.

- install-lefthook/translation-pairing-merge specs junctioned the real
  scripts/ and tsx package into fixtures; Windows recursive deletion
  (Node rmSync and git worktree remove) follows MOUNT_POINT junctions and
  deleted the repository's own directories mid-run. Fixtures now unlink
  their reparse points before any recursive removal (shared helper in
  scripts/test-fixture-cleanup.ts).
- workflow-workerthread spawned its worker with an empty env; on Windows
  os.tmpdir() then degrades to the literal relative path undefined\temp,
  so tsx wrote its transform cache into a cwd-relative undefined/
  directory inside the repo. The worker env now injects the host temp
  path on win32 (workerSpawnEnv, platform-parameterized and unit-tested
  on both arms).
- workspace-context spec did not stub USERPROFILE (win32 homedir) or a
  set DSH_HOME, leaking the developer machine's real ~/.dsh/AGENTS.md
  into discovery.
- ui-trajectory client-bundle spec mounted the built artifact without the
  remote/settingsScope provides the locale plugin needs, so the plugin
  never activated and no view registered.
- subagent temp-fixture cleanup lacked the maxRetries Windows handle
  release needs under load (EPERM); added retries to the three affected
  specs and the fixture-cleanup helper.

packages/subagent/subagent/tests/continuation.spec.ts

@@ -53,7 +53,7 @@ class GatedAdapter extends LlmAdapter {
 
 const roots: string[] = []
 afterEach(() => {
-  for (const root of roots.splice(0)) rmSync(root, { recursive: true, force: true })
+  for (const root of roots.splice(0)) rmSync(root, { recursive: true, force: true, maxRetries: 10, retryDelay: 100 })
 })
 
 /** Boot the full continuable stack: loop, persistence, providers, and subagents. */

packages/subagent/subagent/tests/list-children.spec.ts

@@ -28,7 +28,7 @@ type Script = ConstructorParameters<typeof MockAdapter>[0]
 
 const roots: string[] = []
 afterEach(() => {
-  for (const root of roots.splice(0)) rmSync(root, { recursive: true, force: true })
+  for (const root of roots.splice(0)) rmSync(root, { recursive: true, force: true, maxRetries: 10, retryDelay: 100 })
 })
 
 /** Boot the continuable stack with real JSONL session persistence. */

packages/subagent/tool-subagent-control/tests/tool-subagent-control.spec.ts

@@ -47,7 +47,7 @@ const testToolSignal = new AbortController().signal
 
 const roots: string[] = []
 afterEach(() => {
-  for (const root of roots.splice(0)) rmSync(root, { recursive: true, force: true })
+  for (const root of roots.splice(0)) rmSync(root, { recursive: true, force: true, maxRetries: 10, retryDelay: 100 })
 })
 
 async function setupWith(adapter: MockAdapter | GatedAdapter) {