refactor: drop the local path a chunk's translation no longer takes

The translation editor was the only caller of `saveTranslationChunk`, and it
stopped calling it when it started proposing. What is left behind is dead: the
method on `MantraRepository`, its no-op for previews, its implementation in
`DatabaseMantraRepository`, and `MantraDao.saveTranslation` underneath them.

Deleting it rather than leaving it is the point. Two ways to create a
translation chunk, one of which bypasses the quorum, is one too many -- the next
screen wanting one would find it and take it, and the group would end up with a
translation in its name that nobody signed.

The rule it enforced does not go with it. Keeping one translation per source
chunk moved to `ChatMessage.applyInnerEvent`, where the row is now made, in the
commit before this one -- and covers more there than it ever did here, since the
group's other members were always able to leave a duplicate behind.

`MarmotInnerEventDao.deleteByPayloadEventId` loses its only production caller
here and stays. It is a DAO query rather than a private helper, the invariant
behind it is still true and still tested -- a submission's id is the envelope's,
so a superseded payload cannot be un-queued by its own id -- and `MantraDao`'s
remaining `addDialect` and `addArtifactVersion` are in the same position:
reachable now only from `MantraDaoJvmTest`, and a decision about the whole
submit-to-group path rather than about this screen.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

composeApp/src/commonMain/kotlin/press/mantra/compose/database/dao/MantraDao.kt

@@ -11,13 +11,11 @@ import press.mantra.compose.database.MantraDatabase
 import press.mantra.compose.database.model.ChatMessage
 import press.mantra.compose.database.model.MantraArtifactVersion
 import press.mantra.compose.database.model.MantraDialect
-import press.mantra.compose.database.model.MantraTranslationChunk
 import press.mantra.compose.database.model.MarmotInnerEvent
 import press.mantra.compose.database.model.intermdiate.LocalChatRoom
 import press.mantra.compose.nostr.nip30303.ArtifactVersionEvent
 import press.mantra.compose.nostr.nip30303.DialectEvent
 import press.mantra.compose.nostr.nip30303.SubmissionEvent
-import press.mantra.compose.nostr.nip30303.TranslationChunkEvent
 import press.mantra.compose.nostr.nip30303.tags.ArtifactIdTag
 import press.mantra.compose.repository.MantraRepository.Companion.DEFAULT_LICENSE
 import press.mantra.compose.repository.MantraRepository.Companion.DEFAULT_VISIBILITY
@@ -192,60 +190,6 @@ abstract class MantraDao(
         return mantraArtifactVersion
     }
 
-    @Transaction
-    open suspend fun saveTranslation(
-        translationChapterId: String,
-        chunkId: String,
-        text: String,
-        chatRoomId: String,
-        userPublicKey: HexKey,
-    ): MantraTranslationChunk? {
-        // The translation chunk mirrors the source chunk's position.
-        val sourceChunk = database.mantraChunkDao().getChunkById(chunkId) ?: return null
-
-        val translationChunkTemplate = TranslationChunkEvent.build(
-            translationChapterId = translationChapterId,
-            chunkId = chunkId,
-            index = sourceChunk.index,
-            text = text,
-        )
-        val translationChunk = MantraTranslationChunk.fromTranslationChunkEventTemplate(
-            translationChunkEventTemplate = translationChunkTemplate,
-            chatRoomId = chatRoomId,
-            userPublicKey = userPublicKey,
-        ) ?: return null
-
-        return try {
-            // Replace any existing translation chunk for this source chunk. Its id
-            // is derived from the (now changed) content, so it becomes a new row —
-            // drop the old one (and the submission carrying it) to keep one per
-            // source chunk. The submission is found by what it carries, since its
-            // own id is the envelope's rather than the chunk's.
-            database.mantraTranslationChunkDao()
-                .getTranslationChunksByTranslationChapterId(translationChapterId)
-                .filter { it.chunkId == chunkId && it.id != translationChunk.id }
-                .forEach { stale ->
-                    database.mantraTranslationChunkDao().deleteById(stale.id)
-                    database.marmotInnerEventDao().deleteById(stale.id)
-                    database.marmotInnerEventDao().deleteByPayloadEventId(stale.id)
-                }
-
-            database.mantraTranslationChunkDao().upsert(translationChunk)
-
-            submitToGroup(
-                chatRoomId = chatRoomId,
-                submitterPublicKey = userPublicKey,
-                payload = rumorOf(translationChunkTemplate, userPublicKey),
-                text = "Translated chunk ${translationChunk.index}", // TODO: Use a portion of the translation and name the language
-            )
-
-            translationChunk
-        } catch (error: Throwable) {
-            logger.e("Failed to save translation for chunk $chunkId", error)
-            null
-        }
-    }
-
     private suspend fun sendMarmotInnerEvent(
         chatRoomId: String,
         userPublicKey: HexKey,

composeApp/src/commonMain/kotlin/press/mantra/compose/database/repository/DatabaseMantraRepository.kt

@@ -14,7 +14,6 @@ import press.mantra.compose.database.model.MantraTranslationChapter
 import press.mantra.compose.database.model.MantraTranslationChunk
 import press.mantra.compose.database.model.MarmotInnerEvent
 import press.mantra.compose.database.model.intermdiate.LocalChatRoom
-import press.mantra.compose.nostr.nip30303.TranslationChunkEvent
 import press.mantra.compose.repository.MantraRepository
 
 class DatabaseMantraRepository(
@@ -51,22 +50,6 @@ class DatabaseMantraRepository(
     override suspend fun getChunk(id: String): MantraChunk? =
         database.mantraChunkDao().getChunkById(id)
 
-    override suspend fun saveTranslationChunk(
-        translationChapterId: String,
-        chunkId: String,
-        text: String,
-        chatRoomId: String,
-        userPublicKey: HexKey,
-    ): MantraTranslationChunk? {
-        return database.mantraDao().saveTranslation(
-            translationChapterId = translationChapterId,
-            chunkId = chunkId,
-            text = text,
-            chatRoomId = chatRoomId,
-            userPublicKey = userPublicKey
-        )
-    }
-
     override suspend fun getTranslationsForArtifact(artifactId: String): List<MantraTranslationArtifactVersion> =
         database.mantraTranslationArtifactVersionDao().getTranslationsByArtifactId(artifactId)
 

composeApp/src/commonMain/kotlin/press/mantra/compose/repository/MantraRepository.kt

@@ -35,20 +35,6 @@ interface MantraRepository {
 
     suspend fun getChunk(id: String): MantraChunk?
 
-    /**
-     * Create or replace the translation of a source chunk within a translation
-     * chapter. Any existing translation chunk for the same (translationChapterId,
-     * chunkId) is replaced. Returns the saved chunk, or null if the source chunk
-     * can't be found.
-     */
-    suspend fun saveTranslationChunk(
-        translationChapterId: String,
-        chunkId: String,
-        text: String,
-        chatRoomId: String,
-        userPublicKey: HexKey,
-    ): MantraTranslationChunk?
-
     suspend fun getTranslationsForArtifact(artifactId: String): List<MantraTranslationArtifactVersion>
 
     suspend fun getTranslation(id: String): MantraTranslationArtifactVersion?
@@ -100,14 +86,6 @@ interface MantraRepository {
 
             override suspend fun getChunk(id: String): MantraChunk? = null
 
-            override suspend fun saveTranslationChunk(
-                translationChapterId: String,
-                chunkId: String,
-                text: String,
-                chatRoomId: String,
-                userPublicKey: HexKey,
-            ): MantraTranslationChunk? = null
-
             override suspend fun getTranslationsForArtifact(artifactId: String): List<MantraTranslationArtifactVersion> = emptyList()
 
             override suspend fun getTranslation(id: String): MantraTranslationArtifactVersion? = null