fix(deploy): curl -s 改为 curl -sf，修复 HTTP 404 不被检测的问题

curl -s 只是静默输出，HTTP 404 仍然返回 exit code 0，导致就绪
检查在 Kafka Connect REST API 未初始化完时就通过了。
-f 标志让 curl 在 HTTP 4xx/5xx 时返回非零 exit code。

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/services/deploy.sh

@@ -205,7 +205,7 @@ up() {
     # Note: check /connectors not / — Jetty responds on / before Kafka Connect REST is initialized
     log_info "Waiting for Debezium Connect REST API to be ready..."
     for i in {1..60}; do
-        if curl -s http://localhost:8084/connectors > /dev/null 2>&1; then
+        if curl -sf http://localhost:8084/connectors > /dev/null 2>&1; then
             log_info "Debezium Connect REST API is ready!"
             break
         fi

backend/services/scripts/debezium/register-connectors.sh

@@ -55,7 +55,7 @@ echo "Force: $FORCE"
 echo ""
 echo "Waiting for Debezium Connect REST API to be ready..."
 for i in $(seq 1 $MAX_RETRIES); do
-    if curl -s "$CONNECT_URL/connectors" > /dev/null 2>&1; then
+    if curl -sf "$CONNECT_URL/connectors" > /dev/null 2>&1; then
         echo "Debezium Connect REST API is ready!"
         break
     fi
@@ -70,7 +70,7 @@ done
 # Check existing connectors
 echo ""
 echo "Checking existing connectors..."
-EXISTING=$(curl -s "$CONNECT_URL/connectors")
+EXISTING=$(curl -sf "$CONNECT_URL/connectors" 2>/dev/null || echo "[]")
 echo "Existing connectors: $EXISTING"
 
 # Substitute environment variables in JSON config