fix(gallery): forward imeta poster when adding media to gallery

The "Add Media to Gallery" action in the zoomable view passed only
blurhash, dim, hash, and mime type — losing the poster URL that the
underlying NIP-71 imeta carries on its `image` field. The resulting
ProfileGalleryEntryEvent therefore had no `image` tag, and the
gallery card fell back to the play-icon placeholder for any HLS URL
because the .m3u8 playlist itself can't be decoded as an image.

Thread the poster through Account.addToGallery and
AccountViewModel.addMediaToGallery as an optional `image` parameter,
and pull it from the MediaUrlVideo's artworkUri at the call site.
Non-video content (MediaUrlImage, etc.) still passes null.

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

amethyst/src/main/java/com/vitorpamplona/amethyst/model/Account.kt

@@ -135,6 +135,7 @@ import com.vitorpamplona.quartz.experimental.profileGallery.blurhash
 import com.vitorpamplona.quartz.experimental.profileGallery.dimension
 import com.vitorpamplona.quartz.experimental.profileGallery.fromEvent
 import com.vitorpamplona.quartz.experimental.profileGallery.hash
+import com.vitorpamplona.quartz.experimental.profileGallery.image
 import com.vitorpamplona.quartz.experimental.profileGallery.mimeType
 import com.vitorpamplona.quartz.marmot.mip00KeyPackages.KeyPackageEvent
 import com.vitorpamplona.quartz.marmot.mls.group.MlsGroupStateStore
@@ -2547,6 +2548,7 @@ class Account(
         hash: String?,
         mimeType: String?,
         thumbhash: String? = null,
+        image: String? = null,
     ) {
         val template =
             ProfileGalleryEntryEvent.build(url) {
@@ -2556,6 +2558,7 @@ class Account(
                 dim?.let { dimension(it) }
                 blurhash?.let { blurhash(it) }
                 thumbhash?.let { galleryThumbhash(it) }
+                image?.let { image(it) }
             }
 
         val event = signer.sign(template)

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/components/ZoomableContentView.kt

@@ -940,7 +940,12 @@ fun ShareMediaAction(
                             if (videoUri != null) {
                                 val n19 = Nip19Parser.uriToRoute(postNostrUri)?.entity as? NEvent
                                 if (n19 != null) {
-                                    accountViewModel.addMediaToGallery(n19.hex, videoUri, n19.relay.getOrNull(0), blurhash, dim, hash, mimeType)
+                                    // Forward the imeta poster (only MediaUrlVideo carries it) so HLS
+                                    // gallery entries have a still to render — without this, a video
+                                    // event whose imeta only contains a .m3u8 URL renders as a black
+                                    // play-icon tile in the gallery.
+                                    val posterUrl = (content as? MediaUrlVideo)?.artworkUri
+                                    accountViewModel.addMediaToGallery(n19.hex, videoUri, n19.relay.getOrNull(0), blurhash, dim, hash, mimeType, image = posterUrl)
                                     accountViewModel.toastManager.toast(R.string.media_added, R.string.media_added_to_profile_gallery)
                                 }
                             }

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/AccountViewModel.kt

@@ -856,7 +856,8 @@ class AccountViewModel(
         dim: DimensionTag?,
         hash: String?,
         mimeType: String?,
-    ) = launchSigner { account.addToGallery(hex, url, relay, blurhash, dim, hash, mimeType) }
+        image: String? = null,
+    ) = launchSigner { account.addToGallery(hex, url, relay, blurhash, dim, hash, mimeType, image = image) }
 
     fun removeFromMediaGallery(note: Note) = launchSigner { account.removeFromGallery(note) }