fix: notification pushes now match what the 2023 client reads

Most pushes were still shaped for the 2020 watch, so the 2023 client
parsed them as empty or dropped them without any error.

- RelationshipChanged carries the relationship row, to both players, on
  friend request / accept / remove / add and on favorite / mute / ignore.
  Friend requests and accepts also land in the notifications inbox.
- ModerationKick uses the client's flat moderation block, with the
  reason in VoteKickReason (the only field the dialog shows).
- Bans, account deletion, password resets and second-session takeover
  are a Logout with a numeric reason instead of a kick to the dorm; the
  old string reason failed the client's parse.
- SubscribeToPlayers is honoured: each connection joins a presence group
  per subscribed player, and presence (only presence) reaches subscribers
  as well as friends. The hub allows 180 s of client silence, since the
  client reconnects at most 3 times per login.
- Admin broadcast sends its text as a coach message and can start the
  client's own maintenance countdown; ServerMaintenance only reads
  StartsInMinutes.
- ConsumableMapping, StorefrontBalance, gift, player event, level-up,
  RoomUpdate, profile-image and PlayerLeftChat pushes carry the client's
  DTOs. "Join rejected" is the client's RequestGameInvite message.

Contract in docs/recroom-2023-notifications.md; push frames are checked
by NotificationContractTests through a capturing hub context.

DorkNet.Server/Startup/ServiceCollectionExtensions.cs

@@ -416,15 +416,18 @@ public static class ServiceCollectionExtensions
             kopts.Limits.MinResponseDataRate = null;
         });
 
-        // Keepalive cadence: server pings every 10s, gives the client 60s
-        // to ack before declaring the connection dead. The 10s ping forces
-        // frame traffic well below every proxy timeout we've seen in the
-        // path (Cloudflare edge ~100s, cloudflared 600s, Coolify/Traefik
-        // 180s, Kestrel 130s).
+        // Keepalive cadence: the server pings every 10s, which keeps frame
+        // traffic well below every proxy timeout we've seen in the path
+        // (Cloudflare edge ~100s, cloudflared 600s, Coolify/Traefik 180s,
+        // Kestrel 130s). The 2023 client pings every 15s, but from its main
+        // thread, so a long room-load hitch pauses its pings. It has no
+        // timeout of its own and reconnects at most 3 times per login, so a
+        // healthy socket the server drops can leave it without live
+        // notifications for the rest of the session. Give it 180s.
         var signalR = builder.Services.AddSignalR(opts =>
         {
             opts.KeepAliveInterval = TimeSpan.FromSeconds(10);
-            opts.ClientTimeoutInterval = TimeSpan.FromSeconds(60);
+            opts.ClientTimeoutInterval = TimeSpan.FromSeconds(180);
             opts.HandshakeTimeout = TimeSpan.FromSeconds(15);
             // Allow large gift / community-board payloads (default 32 KB
             // truncates anything bigger and disconnects the client).