Update dependencies and environment for web app

Upgraded '@makerkit/data-loader-supabase-nextjs' to version 1.1.0 and replaced 'autoprefixer' with a newer version. Added new scripts to 'packages.json' and '.env.test' file for test environment. The changes also include removal of unnecessary 'eslint' dependencies and modifications for 'postcss' related dependencies.

.github/workflows/workflow.yml

@@ -87,7 +87,9 @@ jobs:
         run: pnpm run supabase:web:start -- -x studio,migra,deno-relay,pgadmin-schema-diff,imgproxy,logflare
 
       - name: Run App
-        run: pnpm run dev &
+        run: |
+          pnpm --filter web build:test
+          pnpm --filter web start:test
 
       - name: Run Playwright tests
         run: pnpm run test