Remove Flutter dependency in code.

Author: rkistner

packages/powersync/lib/src/log.dart

@@ -1,3 +1,8 @@
 import 'package:logging/logging.dart';
 
+// Duplicate from package:flutter/foundation.dart, so we don't need to depend on Flutter
+const bool kReleaseMode = bool.fromEnvironment('dart.vm.product');
+const bool kProfileMode = bool.fromEnvironment('dart.vm.profile');
+const bool kDebugMode = !kReleaseMode && !kProfileMode;
+
 final isolateLogger = Logger.detached('PowerSync');

packages/powersync/lib/src/powersync_database.dart

@@ -1,7 +1,6 @@
 import 'dart:async';
 import 'dart:isolate';
 
-import 'package:flutter/foundation.dart';
 import 'package:logging/logging.dart';
 import 'package:sqlite_async/sqlite3.dart' as sqlite;
 import 'package:sqlite_async/sqlite_async.dart';
@@ -125,6 +124,7 @@ class PowerSyncDatabase with SqliteQueries implements SqliteConnection {
     if (log == LogType.debug || log == LogType.auto) {
       // Use a detached logger to log directly to the console
       logger = Logger.detached('PowerSync');
+
       final debug = log == LogType.debug || kDebugMode;
       if (debug) {
         logger.level = Level.FINE;