Add unit tests for code coverage improvement

[a6b8]

Summary

Add comprehensive unit test suite to improve code coverage from ~27% to ~67%.

Details

• 32 new test files covering FlowMcpCli public methods and edge cases
• 436 total tests across 41 test suites
• Coverage: 67.35% statements, 67.04% lines
• Theoretical maximum without mocking: ~68.3% (due to CLI entry points, network helpers, init/install flows)
• Excludes index.mjs (CLI entry point with process.argv) from coverage via jest.config.mjs

Test Categories

• Validation (schema validation, config validation, edge cases)
• Tool operations (search, add, remove, list, call)
• Status and health checks
• Cache operations
• Group management
• ZodBuilder edge cases
• Shared lists (resolution, broken files, missing dirs)
• Handlers with shared lists and required libraries
• Auth error handling
• Path edge cases (FIFO, missing files, empty dirs)