fix: hardened backend isolation and debug logs in start.sh

start.sh

@@ -1,18 +1,24 @@
 #!/bin/bash
-# Trigger build: 2026-05-07 08:49
+# Trigger build: 2026-05-07 08:52
 
-if [ "$SERVICE_TYPE" = "backend" ]; then
-    echo "!!! STARTING IN BACKEND-ONLY MODE !!!"
+echo "--- STARTUP DEBUG INFO ---"
+echo "SERVICE_TYPE is: '$SERVICE_TYPE'"
+echo "PROD_BACKEND is: '$PROD_BACKEND'"
+echo "--------------------------"
+
+if [ "$SERVICE_TYPE" = "backend" ] || [ "$PROD_BACKEND" = "true" ]; then
+    echo "!!! CRITICAL: FORCING BACKEND-ONLY MODE !!!"
+    # Kill any accidental Nginx/Node processes
+    pkill nginx || true
+    pkill node || true
+    # Start ONLY uvicorn on the primary HF port
     cd /app/backend && uvicorn app.main:app --host 0.0.0.0 --port 7860
 else
-    echo "!!! STARTING IN FULL-STACK MODE !!!"
-    # Start Backend on internal port
+    echo "!!! STARTING FULL-STACK INTERFACE !!!"
+    # Internal ports: Backend(8000), Frontend(3000)
     cd /app/backend && uvicorn app.main:app --host 0.0.0.0 --port 8000 &
-    
-    # Start Frontend on internal port
     cd /app/frontend && npm run start -- -p 3000 &
     
-    # Start Nginx as the main entry point on HF port 7860
-    echo "Starting Nginx Proxy..."
+    # Nginx as public entry point (7860)
     nginx -g "daemon off;"
 fi