refactor(workflow): cleanup engine re-exports, final verification (Phase 4)

- Remove all re-exports from @uncaged/workflow -> @uncaged/workflow-runtime
- Fix cli-workflow imports to use @uncaged/workflow-runtime for types
- Update bundle-validator to allow @uncaged/workflow-runtime imports
- Update init templates to reference @uncaged/workflow-runtime
- 378 tests passing, build + check clean

Refs #121, relates #125

packages/cli-workflow/package.json

@@ -6,6 +6,7 @@
     "uncaged-workflow": "src/cli.ts"
   },
   "dependencies": {
+    "@uncaged/workflow-runtime": "workspace:*",
     "@uncaged/workflow": "workspace:*",
     "hono": "^4.12.18",
     "yaml": "^2.8.4"