Release v5.2.0 - Add shared library support (Unity DLL)

[Gogoshika-ga]

Added

• Shared library build via -DGA_SHARED_LIB=ON / setup.py --shared
• All GameAnalyticsExtern functions now carry correct GA_API export attributes (__declspec(dllexport) on Windows, visibility("default") on Linux/macOS)
• New exported C API: gameAnalytics_configureBuildPlatform, gameAnalytics_configureCustomLogHandler (GALogHandler + GALoggerMessageType), gameAnalytics_disableDeviceInfo
• sample_shared/ — sample project for shared lib usage
• safeString() helper — null-safe const char* handling for managed runtimes (Unity P/Invoke)
• Cross-platform ga_strndup — replaces POSIX-only strndup, fixes MSVC builds
• setup.py --shared and --compiler (Linux: gcc/clang) flags

Fixed

• Linux/macOS: infinite signal loop freeze — per-signal handler array prevents re-entrant signal delivery looping on exception
• Windows MSVC runtime — use CMAKE_MSVC_RUNTIME_LIBRARY instead of manual /MD//MT flags; shared lib correctly uses /MD (DLL runtime) required for Unity

Changed

• CI matrix now builds both static and shared lib types
• Unit tests skipped for shared builds (internal symbols not exported)
• CI artifact names include -static/-shared suffix

[github-actions]

LCOV of commit 990bf7c during Test Coverage #103

Summary coverage rate:
  lines......: 50.4% (1416 of 2811 lines)
  functions..: 59.9% (236 of 394 functions)
  branches...: no data found

Files changed coverage rate: n/a