Refactor Docker entrypoints and remove unused scripts

- Removed custom entrypoint scripts for backend, frontend, and PostgreSQL services from docker-compose files.
- Added a new entrypoint script in the backend and frontend Dockerfiles to handle initialization without relying on host-mounted scripts.
- Updated Dockerfiles to ensure proper permissions for the new entrypoint scripts.
- Enhanced database initialization logic by moving schema and extension creation to the Alembic migration script.

backend/docker-entrypoint.sh

@@ -0,0 +1,36 @@
+#!/bin/bash
+set -e
+
+# Arranque del contenedor: espera a dependencias, luego ejecuta CMD (uvicorn, gunicorn, celery, …)
+
+# Función para esperar a un puerto TCP usando Python
+wait_for_tcp() {
+  local host=$1
+  local port=$2
+  local service=$3
+  local max_attempts=30
+  local attempt=1
+
+  echo "Esperando a que $service esté disponible en ${host}:${port}..."
+
+  while [ $attempt -le $max_attempts ]; do
+    if python3 -c "import socket; s = socket.socket(); s.settimeout(3); s.connect(('$host', $port)); s.close()" 2>/dev/null; then
+      echo "✓ $service está listo y accesible"
+      return 0
+    fi
+
+    echo "$service no está listo aún... (intento $attempt/$max_attempts)"
+    attempt=$((attempt + 1))
+    sleep 2
+  done
+
+  echo "⚠ WARNING: $service no estuvo disponible después de $max_attempts intentos"
+  echo "   Continuando de todas formas..."
+  return 0
+}
+
+wait_for_tcp "${CORE_DB_HOST:-postgres-a76}" "${CORE_DB_PORT:-5432}" "PostgreSQL"
+wait_for_tcp "keycloak" "8080" "Keycloak"
+
+echo "Iniciando proceso: $*"
+exec "$@"