feat(emoji): surface decrypted private emojis end-to-end

Private emojis stored in the encrypted .content of kind 30030 EmojiPackEvents
were honest about being private but useless: they never appeared in the `:`
autocomplete or the reaction menu, even for the pack owner. This wires up
async decryption so pack owners actually see their private emojis everywhere
public ones already show.

- quartz: add EmojiPackEvent.publicEmojis() / privateEmojis(signer) /
  allEmojis(signer) helpers, mirroring BookmarkListEvent's public/private
  accessor split. privateEmojis() returns null for non-author signers, which
  preserves the rule that foreign packs cannot expose private entries.
- commons: EmojiPackState.mergePack becomes suspend (mergePackWithPrivate)
  and decrypts inside the existing combineTransform hot path; the StateFlow
  consumers (account.emoji.myEmojis → EmojiSuggestionState) get private
  entries automatically once decryption resolves. The combiner already runs
  on Dispatchers.IO so the suspending decrypt does not block the UI.
- amethyst: RenderEmojiPack uses produceState to seed with the public list
  immediately and replace with the merged list once allEmojis(signer)
  resolves — keeps the reaction-menu gallery responsive.
- AddEmojiDialog explainer + KDoc no longer claim private emojis are
  invisible; OwnedEmojiPacksState.toOwnedEmojiPack uses the new accessors.
- Test EmojiPackEventTest covers public/private/all access including the
  foreign-signer case.

https://claude.ai/code/session_01SNG3nj8ZZDChggTsg1qznn

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/model/nip30CustomEmojis/EmojiPackState.kt

@@ -25,9 +25,9 @@ import com.vitorpamplona.amethyst.commons.model.NoteState
 import com.vitorpamplona.amethyst.commons.model.cache.ICacheProvider
 import com.vitorpamplona.quartz.nip01Core.signers.NostrSigner
 import com.vitorpamplona.quartz.nip01Core.tags.aTag.taggedAddresses
+import com.vitorpamplona.quartz.nip30CustomEmoji.EmojiUrlTag
 import com.vitorpamplona.quartz.nip30CustomEmoji.pack.EmojiPackEvent
 import com.vitorpamplona.quartz.nip30CustomEmoji.selection.EmojiPackSelectionEvent
-import com.vitorpamplona.quartz.nip30CustomEmoji.taggedEmojis
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.ExperimentalCoroutinesApi
@@ -81,21 +81,19 @@ class EmojiPackState(
                 emptyList(),
             )
 
-    fun convertEmojiPack(pack: EmojiPackEvent): List<EmojiMedia> =
-        pack.taggedEmojis().map {
-            EmojiMedia(it.code, it.url)
-        }
+    fun convertEmojiPack(pack: EmojiPackEvent): List<EmojiMedia> = pack.publicEmojis().toEmojiMedia()
 
-    fun mergePack(list: Array<NoteState>): List<EmojiMedia> =
+    // Decrypts private (NIP-51) emojis when this signer authored the pack so they
+    // surface alongside public ones in the `:` autocomplete. Foreign packs return
+    // public-only because privateTags refuses to decrypt for non-authors.
+    suspend fun convertEmojiPackWithPrivate(pack: EmojiPackEvent): List<EmojiMedia> = pack.allEmojis(signer).toEmojiMedia()
+
+    private fun List<EmojiUrlTag>.toEmojiMedia() = map { EmojiMedia(it.code, it.url) }
+
+    suspend fun mergePackWithPrivate(list: Array<NoteState>): List<EmojiMedia> =
         list
-            .mapNotNull {
-                val ev = it.note.event as? EmojiPackEvent
-                if (ev != null) {
-                    convertEmojiPack(ev)
-                } else {
-                    null
-                }
-            }.flatten()
+            .mapNotNull { it.note.event as? EmojiPackEvent }
+            .flatMap { convertEmojiPackWithPrivate(it) }
             .distinctBy { it.link }
 
     @OptIn(ExperimentalCoroutinesApi::class)
@@ -105,7 +103,7 @@ class EmojiPackState(
                 if (emojiList != null) {
                     emitAll(
                         combineTransform(emojiList) {
-                            emit(mergePack(it))
+                            emit(mergePackWithPrivate(it))
                         },
                     )
                 } else {
@@ -113,7 +111,7 @@ class EmojiPackState(
                 }
             }.onStart {
                 emit(
-                    mergePack(
+                    mergePackWithPrivate(
                         convertEmojiSelectionPack(
                             getEmojiPackSelection(),
                         )?.map { it.value }?.toTypedArray() ?: emptyArray(),