R9 Web Push in decePub: one subscription per persona, each with its own token and registration

Settings gets "Notifications on this device" (PushEditor): personas, alerts in four groups, policy, a test
notification, after a one-time notice of what the push service learns. Each persona ticked gets its own service
worker registration (push-worker.js at push/{slot}/), so its own endpoint and keys, subscribed with its own token
(IHttpService's *As); nothing PrivaPub stores ties two personas together and the worker never reads the payload's
token. PushService follows the tokens (re-subscribing after a renewal), reconciles at every session start, turns
off before sign-out and drops deleted or suspended personas. A click opens that persona's notifications; the app
badge counts the unread ones. Exchanges now ask for the push scope.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WpVCoDeM1qUTRp4fXQdfof

ClientJsonContext.cs

@@ -27,6 +27,7 @@ namespace decePubClient;
 [JsonSerializable(typeof(ServerInfo))]
 [JsonSerializable(typeof(List<ServerInfo>))]
 [JsonSerializable(typeof(CustomEmojiCache))]
+[JsonSerializable(typeof(PushDevice))]
 [JsonSerializable(typeof(UploadMedia))]
 [JsonSerializable(typeof(ValidationErrors))]
 [JsonSerializable(typeof(WebResult))]