Add Lyng DB contract and SQLite provider skeleton

lyngio/src/jsMain/kotlin/net/sergeych/lyng/io/db/sqlite/PlatformJs.kt

@@ -0,0 +1,37 @@
+/*
+ * Copyright 2026 Sergey S. Chernov real.sergeych@gmail.com
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package net.sergeych.lyng.io.db.sqlite
+
+import net.sergeych.lyng.ScopeFacade
+import net.sergeych.lyng.requireScope
+import net.sergeych.lyng.obj.ObjException
+import net.sergeych.lyng.obj.ObjString
+
+internal actual suspend fun openSqliteBackend(
+    scope: ScopeFacade,
+    core: SqliteCoreModule,
+    options: SqliteOpenOptions,
+): SqliteDatabaseBackend {
+    scope.raiseError(
+        ObjException(
+            core.databaseException,
+            scope.requireScope(),
+            ObjString("SQLite provider is not implemented on this platform yet")
+        )
+    )
+}