Summary

• Create C++20 module interface for logger_system as part of Tier 2 libraries
• Add module directory structure with 4 module files (.cppm)
• Update CMakeLists.txt with optional module support (requires CMake 3.28+)
• Header-based build continues to work during transition period

Module Structure

export module kcenon.logger;

import kcenon.common;           // Required dependency

export import :core;            // Logger, LogContext, LogCollector
export import :backends;        // Integration backends  
export import :analysis;        // Log analysis utilities

Files Added

• src/modules/logger.cppm - Primary module interface
• src/modules/core.cppm - Core partition
• src/modules/backends.cppm - Backends partition
• src/modules/analysis.cppm - Analysis partition

CMake Usage

cmake -DLOGGER_USE_MODULES=ON ..  # Requires CMake 3.28+

Prerequisites (Completed)

• Remove unnecessary factories ([REFACTOR] Remove unnecessary factories - C++20 Module preparation #274)
• [MODULE] Create C++20 module files for kcenon.common common_system#269 - common_system module (Tier 0)
• [MODULE] Create C++20 module files for kcenon.thread thread_system#371 - thread_system module (Tier 1, optional)

Test plan

• Build without modules (default) - verified passing
• All existing tests pass - verified 10/10 logger_system tests pass
• Build with modules (LOGGER_USE_MODULES=ON) - requires CMake 3.28+

Closes #275