feat(claude-do): UI-Prozess loggt auf Platte (ui-.log) + fehlgeschlagene Hub-

## Problem
Beim DeleteTask-Bug (Fix 352aaa52) gab es null Spuren: Der UI-Prozess (ClaudeDo.App) hat gar kein File-Logging (weder Serilog noch `Microsoft.Extensions.Logging` sind in App/Ui referenziert), und im Worker loggt SignalR fehlgeschlagene Hub-Invocations nur auf Debug (`Microsoft.AspNetCore` steht in `src/ClaudeDo.Worker/Program.cs` Z. 60 auf Warning). Die Ursache ließ sich nur finden, ind

ClaudeDo-Task: d2ae3831-733f-4d40-93d7-70c93da11590

src/ClaudeDo.Worker/Hub/HubExceptionLoggingFilter.cs

@@ -0,0 +1,27 @@
+using Microsoft.AspNetCore.SignalR;
+using Microsoft.Extensions.Logging;
+
+namespace ClaudeDo.Worker.Hub;
+
+/// <summary>
+/// Logs a Warning for any exception thrown out of a hub method body, so a failed UI action
+/// leaves a trace in <c>worker-.log</c> instead of only a generic error at the caller.
+/// Does NOT see an argument-binding failure (e.g. a stray CancellationToken parameter) — SignalR
+/// rejects those while parsing the invocation message, before a hub method is ever dispatched.
+/// </summary>
+public sealed class HubExceptionLoggingFilter(ILogger<HubExceptionLoggingFilter> logger) : IHubFilter
+{
+    public async ValueTask<object?> InvokeMethodAsync(
+        HubInvocationContext invocationContext, Func<HubInvocationContext, ValueTask<object?>> next)
+    {
+        try
+        {
+            return await next(invocationContext);
+        }
+        catch (Exception ex)
+        {
+            logger.LogWarning(ex, "Hub method {Method} failed", invocationContext.HubMethodName);
+            throw;
+        }
+    }
+}