Add service for auto-discovering configuration file locations. The
service searches in prioritized order:
1. JDESCOPING_CONFIG_PATH environment variable
2. Same directory as executable
3. ../JdeScoping.Host/ relative to executable
4. User config directory (~/.jdescoping on Unix, %LOCALAPPDATA%\JdeScoping on Windows)
Includes 9 unit tests covering all search locations, priority order,
edge cases (missing directory, missing appsettings.json), and
cancellation token support.
Joseph Doherty