Add unit tests for BlurParameters and LensController

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>

app/build.gradle.kts

@@ -112,6 +112,9 @@ dependencies {
     // Location
     implementation(libs.play.services.location)
 
+    // Test
+    testImplementation(libs.junit)
+
     // Debug
     debugImplementation(libs.androidx.ui.tooling)
 }