Keep root template state request-scoped so dynamic placeholders stay consistent during chunked renders, add reserve() coverage for non-streamed pages, and add compile/test coverage for the new root render lifecycle.
- Move library code from src/ to lib/WiFiManager/src/
- Move headers from include/ to lib/WiFiManager/include/
- Move library.json to lib/WiFiManager/
- Update platformio.ini with Unity test framework configuration
- Add test structure following PlatformIO unit testing best practices
- Remove empty src/ directory (not needed for library-only projects)