feat(daily-prep): add ClearMyDay hub method

src/ClaudeDo.Worker/Hub/WorkerHub.cs

@@ -581,4 +581,19 @@ public sealed class WorkerHub : Microsoft.AspNetCore.SignalR.Hub
         using var ctx = _dbFactory.CreateDbContext();
         await new DailyNoteRepository(ctx).DeleteAsync(id);
     }
+
+    public async Task<int> ClearMyDay()
+    {
+        await using var ctx = await _dbFactory.CreateDbContextAsync();
+        var ids = await ctx.Tasks.Where(t => t.IsMyDay).Select(t => t.Id).ToListAsync();
+        if (ids.Count == 0) return 0;
+
+        await ctx.Tasks.Where(t => t.IsMyDay)
+            .ExecuteUpdateAsync(s => s.SetProperty(t => t.IsMyDay, false));
+
+        foreach (var id in ids)
+            await _broadcaster.TaskUpdated(id);
+
+        return ids.Count;
+    }
 }