Add build-workflow concurrency and npm cache for JS setup (CI-009/CI-007)

config/languages.yaml

@@ -109,7 +109,7 @@ js:
     - name: node-token
       value:
     - name: node-cache
-      value:
+      value: npm
     - name: node-cache-dependency-path
       value:
   dependencies:

lib/ghb/application.rb

@@ -235,7 +235,13 @@ def workflow_set_defaults
         end
       @new_workflow.env = @old_workflow.env
       @new_workflow.defaults = @old_workflow.defaults || {}
-      @new_workflow.concurrency = @old_workflow.concurrency || {}
+      @new_workflow.concurrency =
+        if @old_workflow.concurrency.any?
+          @old_workflow.concurrency
+        else
+          # Cancel superseded full builds when a PR branch is pushed again.
+          { group: 'build-${{github.ref}}', 'cancel-in-progress': true }
+        end
     end
 
     def collect_required_status_checks

spec/fixtures/workflow_generation/build.yml

@@ -20,6 +20,9 @@ permissions:
   pull-requests: read
 env:
   RUBY-BUNDLER-CACHE: true
+concurrency:
+  group: build-${{github.ref}}
+  cancel-in-progress: true
 jobs:
   variables:
     name: Prepare Variables