rework song rows and now playing, add star to the notification

- star/unstar from the context menu fills the icon, then dismisses
- drop the star badge from album art and song rows
- song rows keep a track-number column (natural order fallback), shrink
  four-digit numbers, and gain right-hand download and duration columns
- the play indicator always sits in the left column, overlaid on cover art
  with an inset primary outline when art is shown
- now playing is left aligned with a star toggle
- the media notification gets a star button backed by a session command

app/src/test/kotlin/com/subtracks/ui/components/ItemContextMenuStarTest.kt

@@ -0,0 +1,76 @@
+package com.subtracks.ui.components
+
+import androidx.activity.ComponentActivity
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.test.assertIsDisplayed
+import androidx.compose.ui.test.junit4.v2.createAndroidComposeRule
+import androidx.compose.ui.test.onNodeWithText
+import androidx.compose.ui.test.performClick
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import com.subtracks.data.model.Song
+import com.subtracks.ui.theme.SubtracksTheme
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertFalse
+import org.junit.Assert.assertTrue
+import org.junit.Rule
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.robolectric.annotation.GraphicsMode
+
+@RunWith(AndroidJUnit4::class)
+@GraphicsMode(GraphicsMode.Mode.NATIVE)
+class ItemContextMenuStarTest {
+    @get:Rule
+    val composeRule = createAndroidComposeRule<ComponentActivity>()
+
+    private val song =
+        Song(
+            sourceId = 1,
+            id = "s1",
+            albumId = "al1",
+            artistId = "ar1",
+            title = "Song",
+            album = "Album",
+            artist = "Artist",
+            duration = 100,
+            track = 1,
+            disc = 1,
+            starred = null,
+            genre = null,
+        )
+
+    @Test
+    fun starringFillsTheIconImmediatelyThenDismisses() {
+        var dismissed = false
+        var starred: Boolean? = null
+        composeRule.setContent {
+            SubtracksTheme {
+                var show by remember { mutableStateOf(true) }
+                if (show) {
+                    ItemContextMenu(
+                        target = MenuTarget.Song(song),
+                        actions = ItemActions(setStar = { _, _, value -> starred = value }),
+                        onDismiss = {
+                            dismissed = true
+                            show = false
+                        },
+                    )
+                }
+            }
+        }
+
+        composeRule.mainClock.autoAdvance = false
+        composeRule.onNodeWithText("Star").performClick()
+        composeRule.mainClock.advanceTimeBy(100)
+
+        composeRule.onNodeWithText("Unstar").assertIsDisplayed()
+        assertEquals(true, starred)
+        assertFalse("the menu should stay open so the new icon is visible", dismissed)
+
+        composeRule.mainClock.advanceTimeBy(1_000)
+        assertTrue("starring should dismiss the menu", dismissed)
+    }
+}

app/src/test/kotlin/com/subtracks/ui/library/TrackTimeTest.kt

@@ -0,0 +1,21 @@
+package com.subtracks.ui.library
+
+import org.junit.Assert.assertEquals
+import org.junit.Test
+
+class TrackTimeTest {
+    @Test
+    fun minutesAndSecondsAreZeroPadded() {
+        assertEquals("04:11", formatTrackTime(251))
+    }
+
+    @Test
+    fun anHourOrLongerUsesTheHourWithoutPadding() {
+        assertEquals("1:02:03", formatTrackTime(3_723))
+    }
+
+    @Test
+    fun negativeDurationsClampToZero() {
+        assertEquals("00:00", formatTrackTime(-5))
+    }
+}