Fix worker startup: run as module, add package init

start.sh

@@ -1,11 +1,22 @@
 #!/bin/sh
 set -eu
 
+export PYTHONUNBUFFERED=1
+export PYTHONPATH=/app
+
 python -u -m backend.worker.worker &
 WORKER_PID=$!
 
+cleanup() {
+  kill "$WORKER_PID" 2>/dev/null || true
+}
+trap cleanup EXIT
+
 uvicorn health_api:app --host 0.0.0.0 --port "${PORT:-7860}" &
-UVICORN_PID=$!
+API_PID=$!
+
+wait -n "$WORKER_PID" "$API_PID"
+STATUS=$?
 
-wait "$UVICORN_PID"
-kill "$WORKER_PID" 2>/dev/null || true
+kill "$WORKER_PID" "$API_PID" 2>/dev/null || true
+exit "$STATUS"