fix(installer): stop existing service before smoke test to avoid port conflict

install.sh

@@ -405,6 +405,9 @@ fi
 # ============================================================
 header "── Verification ──"
 
+$SUDO systemctl stop nextwks 2>/dev/null || true
+sleep 1
+
 "$BIN_DIR/core" -config "$CONFIG_FILE" &
 SMOKE_PID=$!
 sleep 2
@@ -412,7 +415,7 @@ sleep 2
 if command -v curl &>/dev/null; then
     RESPONSE=$(curl -s --max-time 3 http://localhost:8080/api/health 2>/dev/null || echo "")
     if [ "$RESPONSE" = '{"status":"ok"}' ]; then
-        success "Server started OK"
+        success "Health check passed"
 
         # Create admin user
         info "Creating admin user..."