workflow: rename dsh-workflow-vm to dsh-workflow-workerthread

Pure mechanical rename now that the package's internals are the
worker-thread engine: directory, package name, spec/e2e filenames,
module tags and logger prefixes, tsconfig/knip/run-gates/AGENTS.md
references, example cordis.yml plugin ids, doc links; catalogs
regenerated and the lockfile refreshed.

scripts/gen-doc-graphs.ts

@@ -191,7 +191,7 @@ const SERVICE_ROLES: ServiceRole[] = [
     pkg: 'workflow',
     title: 'Workflow script engine',
     mode: 'seam',
-    implementations: ['workflow-vm'],
+    implementations: ['workflow-workerthread'],
     consumers: ['tool-workflow'],
     note: 'One engine per context (bash shape, no named-provider registry); the worker-thread engine fans agent() calls out through ctx.subagents.',
   },