Implement comprehensive MCP best practices and security enhancements

[Copilot]

This PR implements comprehensive Model Context Protocol (MCP) best practices and security enhancements to ensure the Binance MCP Server follows industry standards for financial API integration.

Key Improvements

🛡️ Enhanced Security Features

Input Validation & Sanitization:

• Improved symbol validation with special character sanitization and bounds checking
• Enhanced numeric parameter validation with configurable limits
• Comprehensive order parameter validation (side, type, quantity, price)
• Protection against injection attacks and malformed inputs

Secure Error Handling:

• Automatic detection and redaction of sensitive patterns (API keys, secrets) in error messages
• Standardized error response format following MCP specifications
• Protection against information leakage through error messages

Security Infrastructure:

• New security.py module with comprehensive security utilities
• SecurityConfig class for centralized security settings
• SecurityMiddleware for request validation and monitoring
• Audit logging with secure hash generation for tracking

🔧 MCP Protocol Compliance

Server Enhancements:

• Updated server instructions with comprehensive security feature documentation
• Enhanced tool descriptions and metadata following MCP standards
• Improved configuration validation with security checks
• Version updated to 1.2.5 to reflect protocol compliance improvements

Tool Implementation:

• Enhanced create_order tool with comprehensive input validation
• Improved get_order_book tool with better limit parameter handling
• Consistent error handling across all tools
• Proper metadata inclusion in all responses

📊 Testing & Quality

Comprehensive Test Suite:

• Added 16 new security-focused test cases in test_security_validation.py
• Total test coverage increased from 22 to 38 tests (73% increase)
• Tests cover input validation, error sanitization, and security features
• All existing functionality remains intact

📚 Documentation

Security Best Practices:

• Complete security guide (docs/security.md) with implementation details
• MCP compliance documentation (docs/mcp-compliance.md)
• Updated README with security guidelines and MCP compliance information
• Environment variable configuration guide with security considerations

Example Security Improvements

Before:

# Basic validation
if not symbol:
    raise ValueError("Symbol required")

After:

# Enhanced validation with sanitization
def validate_symbol(symbol: str) -> str:
    if not symbol or not isinstance(symbol, str):
        raise ValueError("Symbol must be a non-empty string")
    
    # Sanitize and validate
    sanitized = ''.join(c for c in symbol.upper().strip() if c.isalnum())
    
    if len(sanitized) < 3 or len(sanitized) > 20:
        raise ValueError("Symbol must be 3-20 characters long")
    
    if sanitized.startswith(('0','1','2','3','4','5','6','7','8','9')):
        raise ValueError("Symbol cannot start with a number")
    
    return sanitized

Error Message Sanitization:

# Automatic redaction of sensitive data
message = "Error with API key abc123def456ghi789..."
sanitized = _sanitize_error_message(message)
# Result: "Error with API key [REDACTED]"

Benefits

• Security: Comprehensive protection against common vulnerabilities
• Compliance: Full adherence to MCP protocol standards
• Reliability: Enhanced error handling and input validation
• Maintainability: Well-documented security practices and guidelines
• Production-Ready: Suitable for secure financial API integration

All changes maintain backward compatibility while significantly enhancing security and MCP compliance.

Fixes #46.

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