First test coverage for the project: 17 tests covering BlurParameters
constraint clamping (size, blur, falloff, aspect ratio, position),
data class equality, field preservation across with* methods, and
LensController pre-initialization edge cases.
Adds JUnit 4.13.2 as a test dependency.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
