fix: add test for checking existannce of public/hash.txt file

.github/workflows/validate.yaml

@@ -82,6 +82,25 @@ jobs:
       - uses: actions/setup-node@v3
         with:
           node-version: 18
+      - name: Validate hash.txt file
+        run: |
+          response=$(curl -s -w "%{http_code}" -o /tmp/hash.txt http://localhost:3000/hash.txt)
+          http_code=${response: -3}
+          if [ "$http_code" -ne 200 ]; then
+            echo "Error: HTTP request failed with status code $http_code"
+            exit 1
+          fi
+          mime_type=$(file --mime-type -b /tmp/hash.txt)
+          if [ "$mime_type" != "text/plain" ]; then
+            echo "Error: hash.txt does not have MIME type text/plain. Found: $mime_type"
+            exit 1
+          fi
+          content_length=$(wc -c < /tmp/hash.txt | xargs)
+          if [ "$content_length" -ge 100 ]; then
+            echo "Error: hash.txt content exceeds 100 characters. Length: $content_length"
+            exit 1
+          fi
+          echo "hash.txt is valid with MIME type $mime_type and length $content_length characters."
       - name: Run install
         run: npm ci
       - run: npx playwright install