feat(android): Home per-section empty messages (audit v3 §4.5)

Audit v3 §4.5: Flutter renders explanatory copy for each empty Home
section ("No forgotten favourites yet. Like albums or artists to
fill this in." for Rediscover, "Play some music..." for Most played,
etc). Android was hiding empty sections entirely, which made the
home view look sparse even when 2-3 sections had data and contributed
to the user's emulator complaint about missing rows.

Now: every section slot renders either the populated HorizontalScrollRow
OR an EmptySection card (sentence-case title + understated body copy)
so the page structure is always visible. Playlists row keeps its
"hide-when-empty" behaviour for now since it leads the page — empty
copy at the top would feel like an error.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

android/app/src/main/java/com/fabledsword/minstrel/home/ui/HomeScreen.kt

@@ -10,6 +10,7 @@ import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.PaddingValues
 import androidx.compose.foundation.layout.Spacer
 import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.height
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.layout.size
@@ -269,31 +270,79 @@ private fun HomeSuccessContent(
         if (sections.playlists.isNotEmpty()) {
             item { PlaylistsRow(sections.playlists, onPlaylistClick) }
         }
-        if (sections.recentlyAddedAlbums.isNotEmpty()) {
-            item {
+        item {
+            if (sections.recentlyAddedAlbums.isNotEmpty()) {
                 AlbumsRow("Recently added", sections.recentlyAddedAlbums, onAlbumClick)
+            } else {
+                EmptySection(
+                    title = "Recently added",
+                    body = "Albums you add to the library will show up here first.",
+                )
             }
         }
-        if (sections.rediscoverAlbums.isNotEmpty() || sections.rediscoverArtists.isNotEmpty()) {
-            item {
+        item {
+            if (sections.rediscoverAlbums.isNotEmpty() ||
+                sections.rediscoverArtists.isNotEmpty()
+            ) {
                 RediscoverBlock(
                     albums = sections.rediscoverAlbums,
                     artists = sections.rediscoverArtists,
                     onAlbumClick = onAlbumClick,
                     onArtistClick = onArtistClick,
                 )
+            } else {
+                EmptySection(
+                    title = "Rediscover",
+                    body = "No forgotten favourites yet. Like albums or " +
+                        "artists to fill this in.",
+                )
             }
         }
-        if (sections.mostPlayedTracks.isNotEmpty()) {
-            item { MostPlayedRow(sections.mostPlayedTracks, onAlbumClick) }
+        item {
+            if (sections.mostPlayedTracks.isNotEmpty()) {
+                MostPlayedRow(sections.mostPlayedTracks, onAlbumClick)
+            } else {
+                EmptySection(
+                    title = "Most played",
+                    body = "Play some music — your most-listened tracks will appear here.",
+                )
+            }
         }
-        if (sections.lastPlayedArtists.isNotEmpty()) {
-            item { ArtistsRow("Last played", sections.lastPlayedArtists, onArtistClick) }
+        item {
+            if (sections.lastPlayedArtists.isNotEmpty()) {
+                ArtistsRow("Last played", sections.lastPlayedArtists, onArtistClick)
+            } else {
+                EmptySection(
+                    title = "Last played",
+                    body = "Recently played artists will show up here.",
+                )
+            }
         }
         item { Spacer(Modifier.height(BOTTOM_PADDING_FOR_MINIPLAYER_DP.dp)) }
     }
 }
 
+@Composable
+private fun EmptySection(title: String, body: String) {
+    Column(
+        modifier = Modifier
+            .fillMaxWidth()
+            .padding(horizontal = 16.dp, vertical = 12.dp),
+    ) {
+        Text(
+            text = title,
+            style = MaterialTheme.typography.titleLarge,
+            color = MaterialTheme.colorScheme.onBackground,
+        )
+        Spacer(Modifier.height(4.dp))
+        Text(
+            text = body,
+            style = MaterialTheme.typography.bodySmall,
+            color = MaterialTheme.colorScheme.onSurfaceVariant,
+        )
+    }
+}
+
 /**
  * Rediscover may have both an albums sub-row and an artists sub-row. When
  * both are present the artist row gets an empty title so the section