feat: Now Playing screen MVP (nb. layout xml and Compose UI are two different sources)

app/src/main/java/at/lockstep/player/MainActivity.kt

@@ -0,0 +1,43 @@
+package at.lockstep.player
+
+import android.os.Bundle
+import androidx.activity.ComponentActivity
+import androidx.activity.compose.setContent
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Surface
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableFloatStateOf
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Modifier
+import at.lockstep.player.ui.NowPlayingScreen
+import at.lockstep.player.ui.NowPlayingUiState
+
+class MainActivity : ComponentActivity() {
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        setContent {
+            MaterialTheme {
+                Surface(modifier = Modifier.fillMaxSize()) {
+                    var progress by remember { mutableFloatStateOf(0f) }
+                    var playing by remember { mutableStateOf(false) }
+                    NowPlayingScreen(
+                        state = NowPlayingUiState(
+                            title = "No track",
+                            artist = "—",
+                            progress = progress,
+                            durationSeconds = 180,
+                            isPlaying = playing,
+                        ),
+                        onProgressChange = { progress = it },
+                        onPrevious = { /* TODO: service / JNI */ },
+                        onTogglePlayPause = { playing = !playing },
+                        onNext = { /* TODO: service / JNI */ },
+                    )
+                }
+            }
+        }
+    }
+}