feat: add board detail create entity reference model

app/src/main/java/space/hackenslacker/kanbn4droid/app/boarddetail/BoardDetailModels.kt

@@ -25,6 +25,10 @@ data class BoardTagSummary(
     val colorHex: String,
 )
 
+data class CreatedEntityRef(
+    val publicId: String?,
+)
+
 sealed interface CardBatchMutationResult {
     data object Success : CardBatchMutationResult
     data class PartialSuccess(

app/src/test/java/space/hackenslacker/kanbn4droid/app/boarddetail/BoardDetailModelsTest.kt

@@ -6,6 +6,15 @@ import org.junit.Test
 
 class BoardDetailModelsTest {
 
+    @Test
+    fun createdEntityRef_allowsMissingPublicIdForFallbackVerificationPath() {
+        val withPublicId = CreatedEntityRef(publicId = "card-123")
+        val withoutPublicId = CreatedEntityRef(publicId = null)
+
+        assertEquals("card-123", withPublicId.publicId)
+        assertNull(withoutPublicId.publicId)
+    }
+
     @Test
     fun boardDetailModelsExposeRequiredFields() {
         val tag = BoardTagSummary(