feat(quartz): NIP-78 — add kind 78 normal app data event

NIP-78 was updated (nostr-protocol/nips#2292) to define a second
event kind alongside the existing addressable kind 30078:

- Kind  78: normal event, for apps that need to store and query
  multiple events of the same type. Recommended to use unique tags
  (including `d` tags) for grouping related events; the `d` tag here
  is a grouping key only, not an addressing key.

Add `AppDataEvent` (kind 78) extending `Event`, mirroring the
ergonomics of `AppSpecificDataEvent` (kind 30078): optional `d` tag
hoisted into `tags`, NIP-31 `alt` tag injected when absent, and a
`signer.sign(...)` factory. Register it in `EventFactory` so
incoming kind-78 events deserialize into the typed class.

The existing kind-30078 implementation remains compliant with the
updated spec.

quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/nip78AppData/AppDataEvent.kt

@@ -0,0 +1,81 @@
+/*
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip78AppData
+
+import androidx.compose.runtime.Immutable
+import com.vitorpamplona.quartz.nip01Core.core.Event
+import com.vitorpamplona.quartz.nip01Core.core.HexKey
+import com.vitorpamplona.quartz.nip01Core.signers.NostrSigner
+import com.vitorpamplona.quartz.nip01Core.tags.dTag.dTag
+import com.vitorpamplona.quartz.nip31Alts.AltTag
+import com.vitorpamplona.quartz.utils.TimeUtils
+
+/**
+ * NIP-78 — Arbitrary custom app data, normal-event flavor.
+ *
+ * Kind 78 is the non-replaceable counterpart to [AppSpecificDataEvent] (kind
+ * 30078). Use it when an app needs to store and query multiple events of the
+ * same type. The spec recommends using unique tags (including `d` tags) for
+ * grouping related events; the `d` tag here does NOT make the event
+ * addressable, it is just a free-form grouping key.
+ */
+@Immutable
+class AppDataEvent(
+    id: HexKey,
+    pubKey: HexKey,
+    createdAt: Long,
+    tags: Array<Array<String>>,
+    content: String,
+    sig: HexKey,
+) : Event(id, pubKey, createdAt, KIND, tags, content, sig) {
+    fun dTag(): String = tags.dTag()
+
+    companion object {
+        const val KIND = 78
+        const val ALT = "Arbitrary app data"
+
+        suspend fun create(
+            content: String,
+            dTag: String? = null,
+            otherTags: Array<Array<String>> = emptyArray(),
+            signer: NostrSigner,
+            createdAt: Long = TimeUtils.now(),
+        ): AppDataEvent {
+            val withD =
+                if (dTag == null) {
+                    otherTags
+                } else if (otherTags.any { it.size > 1 && it[0] == "d" && it[1] == dTag }) {
+                    otherTags
+                } else {
+                    otherTags.filter { it.isEmpty() || it[0] != "d" }.toTypedArray() + arrayOf(arrayOf("d", dTag))
+                }
+
+            val newTags =
+                if (withD.none { it.isNotEmpty() && it[0] == "alt" }) {
+                    withD + arrayOf(AltTag.assemble(ALT))
+                } else {
+                    withD
+                }
+
+            return signer.sign(createdAt, KIND, newTags, content)
+        }
+    }
+}

quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/utils/EventFactory.kt

@@ -218,6 +218,7 @@ import com.vitorpamplona.quartz.nip72ModCommunities.approval.CommunityPostApprov
 import com.vitorpamplona.quartz.nip72ModCommunities.definition.CommunityDefinitionEvent
 import com.vitorpamplona.quartz.nip72ModCommunities.follow.CommunityListEvent
 import com.vitorpamplona.quartz.nip75ZapGoals.GoalEvent
+import com.vitorpamplona.quartz.nip78AppData.AppDataEvent
 import com.vitorpamplona.quartz.nip78AppData.AppSpecificDataEvent
 import com.vitorpamplona.quartz.nip7DThreads.ThreadEvent
 import com.vitorpamplona.quartz.nip84Highlights.HighlightEvent
@@ -322,6 +323,7 @@ class EventFactory {
                 AppCurationSetEvent.KIND -> AppCurationSetEvent(id, pubKey, createdAt, tags, content, sig)
                 AppDefinitionEvent.KIND -> AppDefinitionEvent(id, pubKey, createdAt, tags, content, sig)
                 AppRecommendationEvent.KIND -> AppRecommendationEvent(id, pubKey, createdAt, tags, content, sig)
+                AppDataEvent.KIND -> AppDataEvent(id, pubKey, createdAt, tags, content, sig)
                 AppSpecificDataEvent.KIND -> AppSpecificDataEvent(id, pubKey, createdAt, tags, content, sig)
                 AttestationEvent.KIND -> AttestationEvent(id, pubKey, createdAt, tags, content, sig)
                 AttestationRequestEvent.KIND -> AttestationRequestEvent(id, pubKey, createdAt, tags, content, sig)