Add tests that exercise the built package, not just source

.github/workflows/test-build.yaml

@@ -37,3 +37,8 @@ jobs:
         pnpm run lint
         pnpm run test
         pnpm build
+
+    - name: Verify the built package loads under Vitest
+      run: |
+        pnpm run test:dist
+        pnpm run test:consumer-smoke

.gitignore

@@ -1,6 +1,13 @@
 /dist/
 /node_modules/
 /dev/node_modules/
+/e2e/consumer-smoke/node_modules/
+/e2e/consumer-smoke/sci-react-ui.tgz
+/e2e/consumer-smoke-legacy-vitest/node_modules/
+/e2e/consumer-smoke-legacy-vitest/sci-react-ui.tgz
+# pnpm auto-generates this stub for the esbuild build-approval prompt
+/e2e/consumer-smoke/pnpm-workspace.yaml
+/e2e/consumer-smoke-legacy-vitest/pnpm-workspace.yaml
 /coverage
 
 *storybook.log

e2e/consumer-smoke-legacy-vitest/package.json

@@ -0,0 +1,23 @@
+{
+  "name": "consumer-smoke-test-legacy-vitest",
+  "private": true,
+  "type": "module",
+  "scripts": {
+    "test": "vitest run"
+  },
+  "dependencies": {
+    "@diamondlightsource/sci-react-ui": "file:./sci-react-ui.tgz"
+  },
+  "devDependencies": {
+    "@emotion/react": "^11.13.3",
+    "@emotion/styled": "^11.13.0",
+    "@mui/icons-material": "^7.0.0",
+    "@mui/material": "^7.0.0",
+    "jsdom": "^29.1.1",
+    "react": "^18.3.1",
+    "react-dom": "^18.3.1",
+    "react-icons": "^5.3.0",
+    "vite": "7.3.5",
+    "vitest": "4.0.18"
+  }
+}