add typescript to dev dependencies

build-support/typescript-compile.coffee

@@ -5,7 +5,7 @@
 # support for it, but it seems appropriate to focus on coffeescript itself first.
 
 '''
-# e.g. run these shell commands from the repo root:
+# e.g. run these shell commands from the repo root (you'll need to have npm installed typescript):
 ; cat > test-map.coffee <<EOF
 y = 3
 

package.json

@@ -49,6 +49,7 @@
     "jison": "~0.4.18",
     "markdown-it": "~13.0.0",
     "puppeteer": "~13.6.0",
+    "typescript": "^5.7.2",
     "underscore": "~1.13.3",
     "webpack": "~5.72.0"
   }