extract startup logic into server/startup.sh for easy customization

Replaces the inline bash -c "..." command in docker-compose with a dedicated
startup.sh script that installs system packages, pip deps, and starts the server.
Add custom setup steps (apt, pip, curl, etc.) in the marked section.

docker-compose.yml

@@ -4,12 +4,7 @@ services:
     container_name: mcp-bash
     restart: unless-stopped
     working_dir: /workspace
-    command: |
-      bash -c "
-        apt-get update -qq &&
-        apt-get install -y --no-install-recommends curl wget git vim nano htop procps jq less unzip &&
-        pip install -q -r /app/requirements.txt &&
-        cd /app && python -u main.py"
+    command: bash /app/startup.sh
     ports:
       - "8000:8000"
     volumes: