chore: update Vitest configuration and adjust e2e fallback tests

- Set minWorkers to 1 in vitest.shared.ts to optimize test execution.
- Modify e2e-fallback-tests.yaml to correctly set the PORT environment variable for backend startup.
- Change db-migrations.tsdown.config.ts to prevent cleaning of the dist directory, ensuring server files remain intact for Docker builds.

.github/workflows/e2e-fallback-tests.yaml

@@ -96,7 +96,7 @@ jobs:
       - name: Start stack-backend on fallback port (8110)
         uses: JarvusInnovations/background-action@2428e7b970a846423095c79d43f759abf979a635 # v1.0.7
         with:
-          run: pnpm -C apps/backend run with-env:test next start --port 8110 &
+          run: PORT=8110 pnpm -C apps/backend run with-env:test pnpm run start &
           wait-on: |
             http://localhost:8110
           tail: true

apps/backend/scripts/db-migrations.tsdown.config.ts

@@ -49,7 +49,9 @@ export default defineConfig({
   inlineOnly: false,
   // Externalize Node.js builtins so they're imported rather than shimmed
   external: [...nodeBuiltins, ...externalPackages],
-  clean: true,
+  // Docker builds the backend server into the same dist directory before this
+  // script. Cleaning here deletes dist/server.mjs from the final image.
+  clean: false,
   // Use banner to add createRequire for CommonJS modules that use require() for builtins
   // The imported require is used by the shimmed __require2 function
   banner: {

vitest.shared.ts

@@ -6,6 +6,7 @@ export default defineConfig({
   test: {
     watch: false,
     pool: 'threads',
+    minWorkers: 1,
     maxWorkers: 8,
     include: ['**/*.test.{js,ts,jsx,tsx}'],
     includeSource: ['**/*.{js,ts,jsx,tsx}'],