🔧 Fix code quality issues in launch.py - remove unused imports and improve logging

[Copilot]

This PR resolves 8 code quality issues identified by static analysis in launch.py, improving code maintainability and performance without changing functionality.

Issues Fixed

Unused Imports (3 issues)

• Removed unused Optional import from typing module
• Removed unused LauncherConfig and LaunchMode imports from unified_launcher module

Logging Performance (4 issues)

• Converted f-string logging calls to lazy % formatting for better performance:
  • logger.warning(f" - {warning}") → logger.warning(" - %s", warning)
  • logger.info(f"Configuration: {config.mode.value} mode") → logger.info("Configuration: %s mode", config.mode.value)
  • logger.info(f"Logging to file: {config.log_file}") → logger.info("Logging to file: %s", config.log_file)
  • logger.error(f"Launch failed: {e}") → logger.error("Launch failed: %s", e)

Exception Handling (1 issue)

• Improved exception handling by adding specific handlers for common exceptions (RuntimeError, ValueError, OSError) before the catch-all Exception handler
• Maintained backward compatibility while providing better error categorization

Benefits

• Performance: Lazy % formatting in logging functions improves performance by avoiding string formatting when logging is disabled
• Code Quality: Removes dead code (unused imports) and follows Python logging best practices
• Error Handling: More specific exception handling provides better debugging information
• Maintainability: Cleaner imports make dependencies more explicit

Testing

All functionality verified:

• ✅ Help output works: python launch.py --help
• ✅ List modes works: python launch.py --list-modes
• ✅ Error handling works correctly
• ✅ No breaking changes to existing behavior

Fixes #531.

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