refine: AOS binary-search refinement, getRadios signature cleanup

Refine AOS crossing to ~500ms via binary search instead of linear stepping; simplify getRadios to take satPos; tidy radar view/viewmodel.

feature/radar/src/main/java/com/rtbishop/look4sat/feature/radar/RadarView.kt

@@ -94,14 +94,21 @@ fun RadarViewCompose(
         animationSpec = infiniteRepeatable(tween(1000)),
         label = "animScale"
     )
-    // Drive the sweep from the animation framework to eliminate state mutation inside the draw block
-    val sweepTransition = rememberInfiniteTransition(label = "sweep")
-    val sweepDegrees by sweepTransition.animateFloat(
-        initialValue = 0f,
-        targetValue = 360f,
-        animationSpec = infiniteRepeatable(tween(SWEEP_DURATION_MS, easing = LinearEasing)),
-        label = "sweepDegrees"
-    )
+    // Drive the sweep from the animation framework to eliminate state mutation inside the draw block.
+    // Only create the infinite transition when the sweep is enabled — otherwise the canvas would
+    // be invalidated every frame for an effect that isn't visible, wasting GPU and battery.
+    val sweepDegrees: Float
+    if (shouldShowSweep) {
+        val sweepTransition = rememberInfiniteTransition(label = "sweep")
+        sweepDegrees by sweepTransition.animateFloat(
+            initialValue = 0f,
+            targetValue = 360f,
+            animationSpec = infiniteRepeatable(tween(SWEEP_DURATION_MS, easing = LinearEasing)),
+            label = "sweepDegrees"
+        )
+    } else {
+        sweepDegrees = 0f
+    }
     val measurer = rememberTextMeasurer()
     val sunPainter = painterResource(R.drawable.ic_sun)
     val moonPainter = painterResource(R.drawable.ic_moon)

feature/radar/src/main/java/com/rtbishop/look4sat/feature/radar/RadarViewModel.kt

@@ -181,7 +181,7 @@ class RadarViewModel(
                 orbitalPos = pos, sunPosition = cachedSunPos, moonPosition = cachedMoonPos
             )
         }
-        processRadios(allRadios, pass.orbitalObject, timeNow)
+        processRadios(allRadios, pos)
         sendPassData(pos)
     }
 
@@ -342,8 +342,8 @@ class RadarViewModel(
         }
     }
 
-    private suspend fun processRadios(radios: List<SatRadio>, orbitalObject: OrbitalObject, time: Long) {
-        val transmitters = satelliteRepo.getRadios(orbitalObject, stationPos, radios, time)
+    private suspend fun processRadios(radios: List<SatRadio>, satPos: OrbitalPos) {
+        val transmitters = satelliteRepo.getRadios(satPos, radios)
         _uiState.update { state ->
             val freq = if (state.transceivers.selectedUuid != null) {
                 val selectedRadio = transmitters.firstOrNull { it.uuid == state.transceivers.selectedUuid }