feat: Implement structured logging with debug mode toggle and request…

[Hahfyeex]

thi spr closes #116

✨ Features:

• Structured logs with multiple levels (ERROR, WARN, INFO, DEBUG, TRACE)
• Debug mode toggle via --debug and --verbose CLI flags
• Request/response logging with timing information
• Sensitive data redaction (configurable)
• Request ID correlation for distributed tracing
• Operation start/complete tracking with duration
• Integration with Soroban event system

📁 New Files:

• src/logging.rs: Core logging implementation
• src/logging_tests.rs: Comprehensive test suite
• examples/logging_example.rs: Usage demonstration
• examples/logging_demo.sh: Interactive demo script
• LOGGING.md: Complete documentation and usage guide

🔧 Modified Files:

• src/lib.rs: Added logging module and contract integration
• src/main.rs: Added CLI flags for logging configuration
• src/transport.rs: Enhanced with request/response logging

🛡️ Security:

• Sensitive data redaction enabled by default
• Configurable redaction patterns
• Log size limits to prevent memory issues
• Production-safe default configuration

🚀 Performance:

• Debug logs filtered at source when disabled
• Minimal overhead for disabled log levels
• Configurable log size truncation
• Optional request correlation

Closes: Structured logs, Debug mode toggle, Request/response logging requirements