feat(android,ios): offer posters and synopses on the library, as the desktop does

The offer appears when metadata is off and there is a library to put
posters on. It says what turning metadata on sends, links to Settings
and never turns anything on itself. "Not now" is stored on the device.
The existing library screenshots now run with metadata on, as their
shelf implies, and a new screenshot covers the offer.

android/app/src/test/java/io/narl/protonstream/ui/ScreenshotTest.kt

@@ -27,6 +27,8 @@ import org.robolectric.annotation.Config
 import org.robolectric.annotation.GraphicsMode
 import uniffi.pstr_android.ArrangementRecord
 import uniffi.pstr_android.EpisodeRecord
+import uniffi.pstr_android.MetadataProvider
+import uniffi.pstr_android.MetadataSettingsRecord
 import uniffi.pstr_android.OfflineRecord
 import uniffi.pstr_android.PaletteRecord
 import uniffi.pstr_android.SeasonRecord
@@ -79,18 +81,23 @@ class ScreenshotTest {
 
     @Test
     fun `the library on a phone`() = capture("library-phone") {
+        LibraryScreen(MATCHED, {}, { _, _ -> }, {}, {}, { _, _ -> }, { _, _ -> }, PaddingValues())
+    }
+
+    @Test
+    fun `the library offering posters while they are off`() = capture("library-phone-offer") {
         LibraryScreen(LIBRARY, {}, { _, _ -> }, {}, {}, { _, _ -> }, { _, _ -> }, PaddingValues())
     }
 
     @Test
     @Config(qualifiers = RobolectricDeviceQualifiers.MediumTablet)
     fun `the library on a tablet`() = capture("library-tablet") {
-        LibraryScreen(LIBRARY, {}, { _, _ -> }, {}, {}, { _, _ -> }, { _, _ -> }, PaddingValues())
+        LibraryScreen(MATCHED, {}, { _, _ -> }, {}, {}, { _, _ -> }, { _, _ -> }, PaddingValues())
     }
 
     @Test
     fun `the library in the light palette`() = captureLight("library-phone-light") {
-        LibraryScreen(LIBRARY, {}, { _, _ -> }, {}, {}, { _, _ -> }, { _, _ -> }, PaddingValues())
+        LibraryScreen(MATCHED, {}, { _, _ -> }, {}, {}, { _, _ -> }, { _, _ -> }, PaddingValues())
     }
 
     @Test
@@ -116,7 +123,7 @@ class ScreenshotTest {
         // reads it from, so the scale is set there.
         val density = LocalDensity.current
         CompositionLocalProvider(LocalDensity provides Density(density.density, fontScale = 1.5f)) {
-            LibraryScreen(LIBRARY, {}, { _, _ -> }, {}, {}, { _, _ -> }, { _, _ -> }, PaddingValues())
+            LibraryScreen(MATCHED, {}, { _, _ -> }, {}, {}, { _, _ -> }, { _, _ -> }, PaddingValues())
         }
     }
 
@@ -293,6 +300,16 @@ class ScreenshotTest {
         val FILM = title("akira", "Akira", listOf(SeasonRecord(null, "Film", listOf(episode(1u, 1u)))))
             .copy(kind = TitleType.FILM, year = 1988u)
 
+        /** [LIBRARY] with posters on, as the shelf above its grid implies. */
+        val MATCHED get() = LIBRARY.copy(
+            metadataSettings = MetadataSettingsRecord(
+                enabled = true,
+                provider = MetadataProvider.ANI_LIST,
+                language = "en",
+                ready = true,
+            ),
+        )
+
         val LIBRARY = AppUiState(
             loading = false,
             titles = listOf(