R9 Web Push, then the honest version: VAPID key, push subscriptions, encrypted pushes, 4.5.0 advertised

The server's VAPID key (PushKeys, made on first need, in Mongo) is the instance API's vapid.public_key and every app's
vapid_key. /api/v1/push/subscription (POST, GET, PUT, DELETE) keeps one subscription per access token, so per persona;
every notification kept (never a filtered one) is queued as a SendPush job for the subscriptions whose alert and policy
admit it, and sent through the `push` client (the safe handler, https only) encrypted as RFC 8291 aes128gcm or the
aesgcm draft with an ES256 VAPID JWT. 404/410 delete the subscription, 429/5xx/timeouts retry, other answers drop the
push. Subscriptions end with their tokens (revocation, sessions ended, suspension, deletion, a restore); backups hold
neither keys nor subscriptions. The walk of every Mastodon 4.3-4.5 client route (docs/MASTODON-API.md) added
conversations/:id/unread, domain_blocks/preview, v2 notifications clear and PUT policy, /oauth/userinfo and stubs, so both
instance APIs now say 4.5.0 (compatible; PrivaPub <release>). The pasture gets a push sink (pushsink.test) and
scenarios/push.sh in batch A.

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

PrivaPub/Services/RootSessions.cs

@@ -15,7 +15,7 @@ namespace PrivaPub.Services
 	}
 
 	// Ends everything a root is signed in with: its /clientapi tokens, through a new SessionStamp (checked by JwtEvents),
-	// and the Mastodon API tokens and authorizations of each of its personas. Used when its password is changed or
+	// and the Mastodon API tokens and authorizations of each of its personas, with their Web Push subscriptions. Used when its password is changed or
 	// recovered, when it signs out everywhere and when it is deleted. End signs out one session only: the device that
 	// asked (its Mastodon tokens it revokes itself).
 	public class RootSessions : IRootSessions
@@ -40,11 +40,14 @@ namespace PrivaPub.Services
 				.Modify(u => u.SessionStamp, Guid.NewGuid().ToString("N"))
 				.Modify(u => u.EndedSessions, new List<EndedSession>())//the new stamp ends those too
 				.ExecuteAsync(token);
-			foreach (var link in await _dbEntities.RootToAvatars.Match(ra => ra.RootId == rootId).ExecuteAsync(token))
+			var links = await _dbEntities.RootToAvatars.Match(ra => ra.RootId == rootId).ExecuteAsync(token);
+			foreach (var link in links)
 			{
 				await _tokens.RevokeBySubjectAsync(link.AvatarId, token);
 				await _authorizations.RevokeBySubjectAsync(link.AvatarId, token);
 			}
+			// their Web Push subscriptions go with their tokens (R9)
+			await Domain.Social.WebPush.Forget(links.Select(l => l.AvatarId).ToList());
 		}
 
 		// remembered as long as one of its tokens could still be valid; the ones that have expired are forgotten meanwhile