Improve Docker output paths and non-Docker compatibility

[Dannyzen]

This PR introduces two main improvements:

1. Enhanced Output Path Handling in acestep/ui/components.py:

• The output directory for generated files (e.g., in Text2Music UI) is now determined by the ACE_OUTPUT_DIR environment variable.
• If ACE_OUTPUT_DIR is not set (e.g., in non-Docker local development), it defaults to a relative path (./outputs), making outputs appear in a directory relative to where the script is run.
• This change resolves issues for users running the application outside of Docker, as it avoids hardcoding the Docker-specific /app/outputs path and improves usability for local development.

2. Docker Compose Configuration Updates (docker-compose.yaml):

• Bind Mounts for Data: Changed volume definitions to use relative path bind mounts (e.g., ./outputs:/app/outputs, ./logs:/app/logs, ./checkpoints:/app/checkpoints) instead of Docker-managed named volumes. This makes outputs, logs, and checkpoints directly accessible in the project directory on the host, simplifying data management.
• Environment Variable for Docker: Added the ACE_OUTPUT_DIR=/app/outputs environment variable to the Docker service. This ensures the application inside the container uses the correct path that aligns with the bind mounts and the updated Python code, directing outputs to the shared host directory.