fix: robustez de sync comprovada no emulador (duplicatas eliminadas)

- ApiClient: IllegalArgumentException de URL vira Network (banner, sem crash);
  DTOs com listas nullable (servidor podia enviar categories/tags: null)
- SyncEngine: mutex global serializa runs (logs BEGIN/END); resolveConflict
  idempotente (não duplica cópia de conflito); registra rekey:<local>→<server>
  em meta para o editor aberto sobreviver à troca de id do create
- ViewModel: resolve(id) em save/delete; createLocal enfileira create único
- Outbox: índice único (noteId, op); DB v2 com fallbackToDestructiveMigration
- proguard: regras corretas de kotlinx.serialization (Companion.serializer)
- README: seção 'Testado em' com os cenários de emulador executados

app/src/main/java/com/labexposed/notas/ui/NotasViewModel.kt

@@ -85,24 +85,36 @@ class NotasViewModel(app: Application) : AndroidViewModel(app) {
                     createdAt = now, updatedAt = now, dirty = true,
                 ),
             )
-            db.outbox().enqueue(OutboxEntity(noteId = id, op = "create", queuedAt = now))
+            // exatamente um create na fila; autosaves seguintes não re-enfileiram
+            if (!db.outbox().has(id, "create")) {
+                db.outbox().enqueue(OutboxEntity(noteId = id, op = "create", queuedAt = now))
+            }
         }
         return id
     }
 
+    /** Nota por id, seguindo rekeys de create (id local → id do servidor). */
+    private suspend fun resolve(id: String): String? {
+        if (db.notes().byId(id) != null) return id
+        val mapped = db.meta().get("rekey:$id") ?: return null
+        return if (db.notes().byId(mapped) != null) mapped else null
+    }
+
     /** Salva edição local + enfileira mutação + agenda sync (debounce no editor). */
-    fun saveNote(
+    suspend fun saveNoteSync(
         id: String,
         title: String,
         format: String,
         categories: List<String>,
         content: String,
-    ) = viewModelScope.launch(Dispatchers.IO) {
-        val existing = db.notes().byId(id) ?: return@launch
+    ) {
+        val targetId = resolve(id) ?: return
+        val existing = db.notes().byId(targetId) ?: return
         val now = System.currentTimeMillis()
         val contentChanged = existing.content != content
         db.notes().upsert(
             existing.copy(
+                id = targetId,
                 title = title,
                 format = format,
                 categories = categories.joinToString(","),
@@ -112,20 +124,34 @@ class NotasViewModel(app: Application) : AndroidViewModel(app) {
                 conflictNote = "",
             ),
         )
-        if (contentChanged && !db.outbox().has(id, "create")) {
-            db.outbox().enqueue(OutboxEntity(noteId = id, op = "update", queuedAt = now))
+        if (contentChanged) {
+            // nota em create pendente já está na fila com o conteúdo atual (upsert acima)
+            if (!db.outbox().has(targetId, "create") && !db.outbox().has(targetId, "update")) {
+                db.outbox().enqueue(OutboxEntity(noteId = targetId, op = "update", queuedAt = now))
+            }
             SyncScheduler.runNow(getApplication(), "autosave")
         }
     }
 
+    fun saveNote(
+        id: String,
+        title: String,
+        format: String,
+        categories: List<String>,
+        content: String,
+    ) = viewModelScope.launch(Dispatchers.IO) {
+        saveNoteSync(id, title, format, categories, content)
+    }
+
     fun deleteNote(id: String) = viewModelScope.launch(Dispatchers.IO) {
-        val note = db.notes().byId(id) ?: return@launch
+        val targetId = resolve(id) ?: return@launch
+        val note = db.notes().byId(targetId) ?: return@launch
         if (note.isLocalOnly) {
-            db.notes().delete(id)
-            db.outbox().dropFor(id)
+            db.notes().delete(targetId)
+            db.outbox().dropFor(targetId)
         } else {
             db.notes().upsert(note.copy(pendingDelete = true, dirty = true, updatedAt = System.currentTimeMillis()))
-            db.outbox().enqueue(OutboxEntity(noteId = id, op = "delete", queuedAt = System.currentTimeMillis()))
+            db.outbox().enqueue(OutboxEntity(noteId = targetId, op = "delete", queuedAt = System.currentTimeMillis()))
             SyncScheduler.runNow(getApplication(), "delete")
         }
     }