chore(#242): bump flutter_local_notifications ^20.1.0 -> ^22.0.1

Resolves flutter_local_notifications_windows to 3.1.1, which fixes the
VS 18.6 / MSVC 14.51 experimental-coroutine build error (upstream #2777 /
#2785) that breaks the Windows build. No SDK bump needed (Flutter 3.44 /
Dart 3.12 satisfy the new plugin's 3.38.1 / 3.10.0 mins).

analyze clean (the 2-major bump did not change our notification API usage);
full suite 406 green.

Part of #230 (unblocks the windows CI job, PR #228).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

pubspec.yaml

@@ -48,7 +48,7 @@ dependencies:
   uuid: ^4.3.3
   flutter_map: ^8.2.2
   latlong2: ^0.9.1
-  flutter_local_notifications: ^20.1.0
+  flutter_local_notifications: ^22.0.1
   crypto: ^3.0.3
   pointycastle: ^4.0.0
   http: ^1.2.0