ci: prepack to check dep tree

.github/workflows/ci.yml

@@ -61,6 +61,14 @@ jobs:
       - name: build API docs in markdown
         run: yarn docs:markdown-for-agoric-documentation-repo
 
+      # Prepack (without cleanup per package) to ensure that type resolution in
+      # dependent packages continues to work when the typedefs are generated by
+      # their upstream packages. This helps avoid a situation in which the types
+      # only resolve because of the state of the local filesystem, and files
+      # when imported in an NPM node_modules tree.
+      - name: Pack packages
+        run: yarn lerna run --reject-cycles --concurrency 1 prepack
+
   test:
     name: test