use Dart script instead of sh script for wasm init

Author: stevensJourney

melos.yaml

@@ -38,7 +38,7 @@ scripts:
       scope:
         - powersync_web_worker
 
-  update:wasm: sh scripts/init_sqlite_wasm.sh
+  update:wasm: dart run scripts/init_sqlite_wasm.dart
 
   test:
     description: Run tests in a specific package.

scripts/init_sqlite_wasm.dart

@@ -0,0 +1,44 @@
+/// Downloads sqlite3.wasm and copies it to all demo folders
+import 'dart:io';
+
+final sqliteUrl =
+    'https://github.com/simolus3/sqlite3.dart/releases/download/sqlite3-2.3.0/sqlite3.wasm';
+
+void main() async {
+  // Create assets directory if it doesn't exist
+  final assetsDir = Directory('assets');
+  if (!await assetsDir.exists()) {
+    await assetsDir.create();
+  }
+
+  final sqliteFilename = 'sqlite3.wasm';
+  final sqlitePath = 'assets/$sqliteFilename';
+
+  // Download sqlite3.wasm
+  await downloadFile(sqliteUrl, sqlitePath);
+
+  await for (var entity in Directory('demos').list()) {
+    if (entity is Directory) {
+      var demoDir = entity;
+      var webDir = Directory('${demoDir.path}/web');
+      if (await webDir.exists()) {
+        await File(sqlitePath).copy('${webDir.path}/$sqliteFilename');
+        print('Copied $sqlitePath to ${webDir.path}');
+      }
+    }
+  }
+}
+
+Future<void> downloadFile(String url, String savePath) async {
+  print('Downloading: $url');
+  var httpClient = HttpClient();
+  var request = await httpClient.getUrl(Uri.parse(url));
+  var response = await request.close();
+  if (response.statusCode == HttpStatus.ok) {
+    var file = File(savePath);
+    await response.pipe(file.openWrite());
+  } else {
+    print(
+        'Failed to download file: ${response.statusCode} ${response.reasonPhrase}');
+  }
+}