delete CloudKit and added BalanceFlutter

BalanceFlutter/scripts/build.sh

@@ -0,0 +1,23 @@
+#!/usr/bin/env bash
+set -euo pipefail
+cd "$(dirname "${BASH_SOURCE[0]}")/.."
+platform="${1:-web}"
+if [[ $# -gt 0 ]]; then shift; fi
+flutter_bin="${FLUTTER_BIN:-flutter}"
+case "$platform" in
+  web|android|ios|macos|windows|linux) ;;
+  watchos)
+    # watchOS uses the existing companion app; Flutter has no watchOS runner.
+    exec xcodebuild -project ../Balance/Balance.xcodeproj -scheme BalanceWatch \
+      -configuration Release -sdk watchsimulator -destination 'generic/platform=watchOS Simulator' \
+      -derivedDataPath build/watchos CODE_SIGNING_ALLOWED=NO build "$@"
+    ;;
+  *) echo "Usage: $0 {web|android|ios|macos|windows|linux|watchos} [build options]" >&2; exit 2 ;;
+esac
+"$flutter_bin" pub get
+case "$platform" in
+  web) "$flutter_bin" build web --release --no-web-resources-cdn "$@" ;;
+  android) "$flutter_bin" build apk --release "$@" ;;
+  ios) "$flutter_bin" build ios --release --no-codesign "$@" ;;
+  *) "$flutter_bin" build "$platform" --release "$@" ;;
+esac

BalanceFlutter/scripts/probe_web_lock.dart

@@ -0,0 +1,73 @@
+// ignore_for_file: avoid_print
+// Compile with `dart compile js scripts/probe_web_lock.dart -o /tmp/web-lock.js`.
+// Run with Node 24.5+ (native navigator.locks) and isSecureContext=true.
+// This tests JS Promise/ownership behavior, not browser/IndexedDB integration.
+import 'dart:async';
+import 'dart:js_interop';
+
+import 'package:balance_flutter/services/runtime_lock_web.dart';
+
+@JS('isSecureContext')
+external set secureContext(bool value);
+
+@JS('navigator')
+external JSObject get navigatorObject;
+
+@JS('navigator.locks')
+external JSObject get lockManager;
+
+@JS('Object.defineProperty')
+external JSObject defineProperty(
+  JSObject target,
+  JSString property,
+  JSObject descriptor,
+);
+
+Future<void> expectFailure(
+  Future<void> Function() action,
+  String message,
+) async {
+  try {
+    await action();
+  } on StateError catch (error) {
+    if (error.message.toString().contains(message)) return;
+    rethrow;
+  }
+  throw StateError('Expected failure containing $message');
+}
+
+Future<void> main() async {
+  secureContext = true;
+  final first = BrowserRuntimeLock();
+  final second = BrowserRuntimeLock();
+  await first.acquire();
+  await expectFailure(first.acquire, 'already held');
+  var acquired = false;
+  final next = second.acquire().then((_) => acquired = true);
+  await Future<void>.delayed(const Duration(milliseconds: 25));
+  if (acquired) throw StateError('Second owner bypassed the origin lock');
+  await first.release();
+  await next;
+  await second.release();
+  await expectFailure(second.release, 'not held');
+
+  secureContext = false;
+  await expectFailure(BrowserRuntimeLock().acquire, 'HTTPS');
+  secureContext = true;
+  final original = lockManager;
+  defineProperty(
+    navigatorObject,
+    'locks'.toJS,
+    {'value': null, 'configurable': true}.jsify() as JSObject,
+  );
+  await expectFailure(BrowserRuntimeLock().acquire, 'Web Locks API');
+  defineProperty(
+    navigatorObject,
+    'locks'.toJS,
+    {'value': original, 'configurable': true}.jsify() as JSObject,
+  );
+  final restored = BrowserRuntimeLock();
+  await restored.acquire();
+  await restored.release();
+  print('Web lock probe passed');
+}