fix(worker): raise SignalR MaximumParallelInvocationsPerClient

Default of 1 serializes every hub call on a connection - a slow one
(GetTicketProjects hitting an unreachable ticket system, 10s timeout)
blocked unrelated calls like UpdateList/UpdateListConfig behind it for
the same duration, making list-settings save appear to hang.

src/ClaudeDo.Worker/Program.cs

@@ -78,10 +78,14 @@ builder.Services.AddHostedService<AttachmentOrphanRecovery>();
 builder.Services.AddHostedService<PromptFileRecovery>();
 builder.Services.AddHostedService<LegacyWorktreeFolderRecovery>();
 builder.Services.AddHostedService<UntrackedWorktreeRecovery>();
-builder.Services.AddSignalR().AddJsonProtocol(options =>
-{
-    options.PayloadSerializerOptions.Converters.Add(new System.Text.Json.Serialization.JsonStringEnumConverter());
-});
+// Default MaximumParallelInvocationsPerClient=1 serializes every hub call on one connection —
+// a slow one (e.g. GetTicketProjects hitting an unreachable ticket system) blocks unrelated
+// calls like UpdateList/UpdateListConfig behind it for the same 10s.
+builder.Services.AddSignalR(options => options.MaximumParallelInvocationsPerClient = 10)
+    .AddJsonProtocol(options =>
+    {
+        options.PayloadSerializerOptions.Converters.Add(new System.Text.Json.Serialization.JsonStringEnumConverter());
+    });
 
 // Runner stack.
 builder.Services.AddSingleton<IClaudeProcess, ClaudeProcess>();