Keylight C++ SDK v0.1.2

Fixed

• Unreal Engine plugin now compiles on clang targets (macOS/Linux/iOS/Android).
  Keylight.Build.cs built the module with C++ exceptions disabled, but the
  SDK's FileStore (which the plugin's UELicenseStore wraps) catches
  std::filesystem_error around its atomic-rename writes. Clang rejected this
  with "cannot use 'try' with exceptions disabled". The module now sets
  bEnableExceptions = true (RTTI stays off; the SDK uses neither
  dynamic_cast nor typeid). The public SDK API remains exception-free.
• Unreal plugin: safe teardown of the licensing client. UKeylightSubsystem
  now declares an out-of-line destructor so its TUniquePtr members (holding
  forward-declared SDK types) are destroyed where those types are complete —
  guaranteeing ~Client() runs (joining the background auto-validation thread)
  instead of being silently skipped against an incomplete type.