build: build ts workspace during root postinstall

Author: konegen

package.json

@@ -3,7 +3,7 @@
   "private": true,
   "description": "Root launcher for the fh-workflow CLI. Delegates to ts/workflow-cli; no dependencies of its own.",
   "scripts": {
-    "postinstall": "npm --prefix ts install",
+    "postinstall": "npm --prefix ts install && npm --prefix ts run build",
     "validate": "node ts/workflow-cli/cli/fh-workflow.mjs validate",
     "check-schema": "node ts/workflow-cli/cli/fh-workflow.mjs check-schema",
     "open": "node ts/workflow-cli/cli/fh-workflow.mjs open",