docs & code : enhance README with comprehensive setup guide and troubleshooting with code changes

[Bvvvp009]

• Add HOST_DATA_DIR documentation and setup instructions
• Improve Docker Compose examples with deployment scenarios
• Add comprehensive troubleshooting section for common issues
• Include performance optimization guidance for different systems
• Enhance configuration documentation with clear examples
• Fix JWT authentication issues and unknown env var warnings
• Add environment variable validation in all entrypoint scripts
• Prevent OP_NODE_L2_ENGINE_AUTH_RAW from being passed to op-node binary

Fixes #536, #438

[cb-heimdall]

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