feat(android): filled heart for liked state, outlined for unliked

Liked tracks now render a filled heart (HeartFilled, defined inline
in LikeButton.kt) instead of just recoloring the outlined heart.
Matches the cross-app convention (Spotify, Apple Music, etc.) where
fill is the affordance change rather than tint alone.

Lucide ships outlined-only by design (jar inspection: heart.kt,
heart_crack.kt, heart_off.kt, etc., none filled). Built the filled
variant locally from Lucide's exact path data so the toggle reads as
a fill swap, not a different shape. No new dep - keeps the project's
Lucide-everywhere icon system consistent.

Operator authorized the divergence 2026-06-01 ("changing to material
for this one symbol... is acceptable"); inline ImageVector route
preserves Lucide visual harmony better than mixing material-icons
just for one glyph.

android/app/src/main/java/com/fabledsword/minstrel/shared/widgets/LikeButton.kt

@@ -5,6 +5,11 @@ import androidx.compose.material3.IconButton
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.runtime.Composable
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.SolidColor
+import androidx.compose.ui.graphics.vector.ImageVector
+import androidx.compose.ui.graphics.vector.path
+import androidx.compose.ui.unit.dp
 import com.composables.icons.lucide.Heart
 import com.composables.icons.lucide.Lucide
 
@@ -14,9 +19,13 @@ import com.composables.icons.lucide.Lucide
  * caller's ViewModel (typically observeIsLiked + toggleLike from
  * LikesRepository), not here.
  *
- * Flutter equivalent is `flutter_client/lib/likes/like_button.dart`.
- * That one tints the heart with the accent color; we do the same via
- * the M3 primary slot so light/dark mode tracks the theme.
+ * Liked state renders a **filled** heart (HeartFilled, defined below);
+ * unliked state renders Lucide's outlined Heart. Both share the same
+ * geometric path so the toggle is a fill swap, not an icon swap —
+ * matches the cross-app pattern (Spotify, Apple Music, etc.). Lucide
+ * ships outlined-only by design; the filled variant is built locally
+ * from the same path data so we keep the project's icon system
+ * consistent (operator 2026-06-01).
  */
 @Composable
 fun LikeButton(
@@ -26,7 +35,7 @@ fun LikeButton(
 ) {
     IconButton(onClick = onToggle, modifier = modifier) {
         Icon(
-            imageVector = Lucide.Heart,
+            imageVector = if (liked) HeartFilled else Lucide.Heart,
             contentDescription = if (liked) "Unlike" else "Like",
             tint = if (liked) {
                 MaterialTheme.colorScheme.primary
@@ -36,3 +45,35 @@ fun LikeButton(
         )
     }
 }
+
+/**
+ * Filled-heart counterpart to [Lucide.Heart], built from the same path
+ * data so the toggle reads as a fill change rather than an icon swap.
+ * Cached as a private lateinit-style backing prop following Lucide's
+ * own pattern (heart.kt in the icons-lucide-cmp jar).
+ */
+private val HeartFilled: ImageVector by lazy {
+    ImageVector.Builder(
+        name = "heart_filled",
+        defaultWidth = 24.dp,
+        defaultHeight = 24.dp,
+        viewportWidth = 24f,
+        viewportHeight = 24f,
+    ).apply {
+        path(
+            fill = SolidColor(Color.Black),
+            stroke = null,
+        ) {
+            moveTo(2f, 9.5f)
+            arcToRelative(5.5f, 5.5f, 0f, false, true, 9.591f, -3.676f)
+            arcToRelative(0.56f, 0.56f, 0f, false, false, 0.818f, 0f)
+            arcTo(5.49f, 5.49f, 0f, false, true, 22f, 9.5f)
+            curveToRelative(0f, 2.29f, -1.5f, 4f, -3f, 5.5f)
+            lineToRelative(-5.492f, 5.313f)
+            arcToRelative(2f, 2f, 0f, false, true, -3f, 0.019f)
+            lineTo(5f, 15f)
+            curveToRelative(-1.5f, -1.5f, -3f, -3.2f, -3f, -5.5f)
+            close()
+        }
+    }.build()
+}