Fix LIVE badge visibility + checkbox contrast

LIVE badge: explicit Color(0xFF00C853) green with white bold text,
no longer uses secondary color scheme which was dark-on-dark.

Checkbox: show faint white RadioButtonUnchecked when not selected so
user can see the selection zone on dark/thumbnail backgrounds.

src/main/kotlin/com/bolenpad/photophetch/ui/DensePhotoGrid.kt

@@ -10,10 +10,12 @@ import androidx.compose.foundation.lazy.LazyListState
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.filled.CheckCircle
 import androidx.compose.material.icons.filled.Image
+import androidx.compose.material.icons.filled.RadioButtonUnchecked
 import androidx.compose.material3.*
 import androidx.compose.runtime.*
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.graphics.ImageBitmap
 import androidx.compose.ui.graphics.toComposeImageBitmap
 import androidx.compose.ui.layout.ContentScale
@@ -255,14 +257,25 @@ private fun DenseThumb(
                 Icon(Icons.Default.CheckCircle, contentDescription = null,
                     tint = MaterialTheme.colorScheme.primary,
                     modifier = Modifier.align(Alignment.TopEnd).padding(2.dp).size(16.dp))
+            } else {
+                // Faint unchecked indicator so user knows cell is tappable
+                Icon(Icons.Default.RadioButtonUnchecked, contentDescription = null,
+                    tint = Color.White.copy(alpha = 0.5f),
+                    modifier = Modifier.align(Alignment.TopEnd).padding(2.dp).size(14.dp))
             }
 
             // Bottom-left: LIVE badge or video size badge
             if (photo.isLivePhotoStill) {
-                Badge(
+                Box(
-                    containerColor = MaterialTheme.colorScheme.secondary.copy(alpha = 0.85f),
+                    modifier = Modifier
-                    modifier = Modifier.align(Alignment.BottomStart).padding(2.dp),
+                        .align(Alignment.BottomStart)
-                ) { Text("LIVE", style = MaterialTheme.typography.labelSmall) }
+                        .padding(3.dp)
+                        .background(Color(0xFF00C853), shape = MaterialTheme.shapes.extraSmall)
+                        .padding(horizontal = 4.dp, vertical = 1.dp),
+                ) {
+                    Text("LIVE", fontSize = 9.sp, fontWeight = FontWeight.Bold,
+                        color = Color.White)
+                }
             } else if (photo.mediaType == MediaType.VIDEO) {
                 val sizeLabel = if (photo.sizeBytes > 1024 * 1024)
                     "▶ ${photo.sizeBytes / (1024 * 1024)}MB"