refactor(modules): update C++20 module files for upstream ecosystem changes (#223)

[kcenon]

Closes #223

Summary

• Align integration.cppm transport types with actual header API signatures (transport_interface, websocket_transport, http_transport, resilient_transport)
• Add error category exports to core.cppm (messaging_error_category, make_messaging_error_code from Issue [Refactor] Define messaging_error_category and typed error codes #229)
• Add resilience type exports to integration.cppm (retry_config, circuit_breaker_config, resilience_statistics from Issue [Refactor] Replace local circuit breaker with common_system resilience module #221)
• Add health check adapter exports to integration.cppm (messaging_health_check, queue_health_check, transport_health_check from Issue [Refactor] Integrate common_system health monitoring API #222)

Changes

core.cppm

• Added messaging_error_category class and make_messaging_error_code() factory function after the existing error codes section

integration.cppm

• Transport API alignment: Replaced outdated transport_options with transport_config + transport_statistics structs matching transport_interface.h
• transport_interface: Fixed disconnect() to return VoidResult, renamed state() to get_state(), replaced send_async() with send_binary(), added set_binary_handler()/set_state_handler(), added get_statistics()/reset_statistics()
• websocket_transport: Now uses websocket_transport_config, includes topic subscription methods (subscribe, unsubscribe, unsubscribe_all, get_subscriptions), send_text(), ping(), set_disconnect_handler()
• http_transport: Added http_content_type enum, http_transport_config, post()/get() methods, set_header()/remove_header()
• resilient_transport: Complete rewrite with retry_config, resilient_transport_config, resilience_statistics, circuit breaker control methods, PIMPL pattern
• Health check adapters: Added map_health_status(), messaging_health_check, queue_health_check, transport_health_check, create_messaging_composite_check(), register_messaging_health_checks()
• Added <format>, <map>, <set> to global module fragment

Test Plan

• Regular build passes (cmake --build)
• All existing tests pass (168/171, 3 pre-existing failures)
• Health check tests pass (test_messaging_health_checks)
• Module build with MESSAGING_BUILD_MODULES=ON (requires CMake 3.28+ and upstream module targets in CI)

[kcenon]

Module Build Verification Results

Configuration Summary

Component	Status	Notes
CMake configure (Ninja + LLVM Clang 21)	Pass	All module targets created
common_system_modules	Configured	COMMON_BUILD_MODULES=ON
thread_system_modules	Configured	THREAD_BUILD_MODULES=ON
container_system_modules	Configured	CONTAINER_BUILD_MODULES=ON
network_system_modules	Configured	NETWORK_BUILD_MODULES=ON
monitoring_system_modules	Configured	MONITORING_ENABLE_MODULES=ON
messaging_system_modules	Configured	MESSAGING_BUILD_MODULES=ON

Issues Found & Fixed

1. INTERFACE library target handling (cmake/UnifiedDependencies.cmake:485):

   • target_compile_definitions() used PUBLIC on INTERFACE library targets
   • Fixed: check TYPE property and use INTERFACE keyword for INTERFACE targets

2. Module target missing upstream include paths (CMakeLists.txt):

   • messaging_system_modules only had its own include/ directory
   • The global module fragment #include <core/container.h> couldn't resolve
   • Fixed: link messaging_system_modules PRIVATE to messaging_system_core for transitive include propagation

3. Non-existent module imports (messaging.cppm, integration.cppm):

   • export import kcenon.logger; — no such module (logging is kcenon.common:logging partition)
   • Fixed: removed kcenon.logger, added kcenon.monitoring

Build Results

Phase	Status	Details
Dependency scanning (clang-scan-deps)	Pass	All 5 .cppm files scan successfully
Upstream module compilation	Blocked	thread_system_modules has naming errors (lockfree_queue vs is_lockfree_queue)
database_system_modules	Blocked	CMake file set base directory bug (upstream)
Header-based build + tests	Pass	168/171 tests pass (3 pre-existing failures)

Conclusion

The messaging_system module files are correctly configured and scan successfully. Full end-to-end module compilation is blocked by upstream module file bugs in thread_system and database_system, which need separate upstream fixes. This is consistent with the test plan note: "requires upstream module targets in CI".