Add web app smoke test with DinD pattern

tests/test.sh

@@ -0,0 +1,54 @@
+#!/bin/bash
+set -euo pipefail
+
+IMAGE="$1"
+FAILED=0
+PASSED=0
+
+TMPDIR="$(mktemp -d)"
+CONTAINER_NAME="test-$(echo "$IMAGE" | tr ':/' '-')-$$"
+trap 'docker rm -f "$CONTAINER_NAME" 2>/dev/null; rm -rf "$TMPDIR"' EXIT
+
+DOCKER_GW=$(docker network inspect bridge --format '{{range .IPAM.Config}}{{.Gateway}}{{end}}')
+BASE_URL="http://${DOCKER_GW}:3000"
+
+assert_eq() {
+  local desc="$1" expected="$2" actual="$3"
+  if [ "$expected" = "$actual" ]; then
+    echo "PASS: $desc"
+    PASSED=$((PASSED + 1))
+  else
+    echo "FAIL: $desc (expected '$expected', got '$actual')"
+    FAILED=$((FAILED + 1))
+  fi
+}
+
+docker run -d --name "$CONTAINER_NAME" -p 3000:3000 "$IMAGE"
+
+echo "Waiting for container..."
+READY=false
+for i in $(seq 1 30); do
+  if curl -s -o /dev/null "$BASE_URL/"; then
+    echo "Container ready (attempt $i)"
+    READY=true
+    break
+  fi
+  sleep 2
+done
+
+if [ "$READY" = false ]; then
+  echo "Container did not become ready within 60s"
+  echo "=== Container logs ==="
+  docker logs "$CONTAINER_NAME" 2>&1 || true
+  exit 1
+fi
+
+STATUS=$(curl -s -o "$TMPDIR/body" -w '%{http_code}' "$BASE_URL/")
+echo "HTTP status: $STATUS"
+assert_eq "HTTP 200" "200" "$STATUS"
+
+echo ""
+echo "$PASSED/$((PASSED + FAILED)) tests passed"
+if [ "$FAILED" -gt 0 ]; then
+  exit 1
+fi