feat: add build_context input and update build step to change directory

.forgejo/actions/build-node-app/action.yaml

@@ -7,6 +7,11 @@ inputs:
     default: test
     required: false
 
+  build_context:
+    description: Build context directory (absolute or relative to GITHUB_WORKSPACE)
+    default: .
+    required: false
+
   build_action:
     description: Name of the build script
     default: build
@@ -43,6 +48,7 @@ runs:
     - name: Build-Node-App Build and Test
       shell: sh
       run: |
+        cd ${{ inputs.build_context }}
         npm install
         npm run ${{ inputs.test_action }}
         npm run ${{ inputs.build_action }}