Add entrypoint.sh: wait for MariaDB before starting Flask

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/entrypoint.sh

@@ -0,0 +1,35 @@
+#!/bin/sh
+set -e
+
+RETRY_INTERVAL=3
+
+# If no db_config.json exists yet, skip the wait (first-run setup mode).
+python - <<'EOF'
+import sys, os
+config_path = os.environ.get("DB_CONFIG_PATH", "/config/db_config.json")
+if not os.path.exists(config_path):
+    sys.exit(1)
+EOF
+DB_CONFIGURED=$?
+
+if [ "$DB_CONFIGURED" -eq 1 ]; then
+    echo "[entrypoint] Keine DB-Konfiguration gefunden – starte im Setup-Modus."
+else
+    echo "[entrypoint] DB-Konfiguration gefunden – warte auf MariaDB..."
+    while true; do
+        python - <<'EOF'
+import sys
+from util.db_config import load_config, test_connection
+config = load_config()
+sys.exit(0 if config and test_connection(config) else 1)
+EOF
+        if [ $? -eq 0 ]; then
+            echo "[entrypoint] MariaDB erreichbar – starte Flask."
+            break
+        fi
+        echo "[entrypoint] MariaDB noch nicht bereit – neuer Versuch in ${RETRY_INTERVAL}s..."
+        sleep "$RETRY_INTERVAL"
+    done
+fi
+
+exec python app.py