Switch online play screens to new header (#37074)

Specifically the one used on the daily challenge screen. Was bugging me
that playlists/multi have that old yellow header design used, so I've
changed it. Will probably come in handy once the footer/leaderboard
changes are in.

Also localized the headers while at it.

Multiplayer:


![osu_2026-03-23_20-03-22](https://github.com/user-attachments/assets/1f262aea-8bf9-412d-9c4a-89addd65bf38)

Playlists:


![osu_2026-03-23_20-34-18](https://github.com/user-attachments/assets/3f7d349e-7c03-4f56-8e57-1c65ae746235)

The only thing I'm wondering about is whether the detail thing
(participant count/playlist length) should be using the highlight colour
here. The old design had them be yellow, but I feel like the pink on
this one stands out too much.

---------

Co-authored-by: Dean Herbert <pe@ppy.sh>

osu.Game/Graphics/UserInterface/SectionHeader.cs

@@ -2,6 +2,7 @@
 // See the LICENCE file in the repository root for full licence text.
 
 using osu.Framework.Allocation;
+using osu.Framework.Bindables;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
 using osu.Framework.Graphics.Shapes;
@@ -14,8 +15,20 @@ namespace osu.Game.Graphics.UserInterface
 {
     public partial class SectionHeader : CompositeDrawable
     {
+        /// <summary>
+        /// Extra text to be shown in brackets next to the header.
+        /// Unlike the header itself, this can be updated during runtime.
+        /// </summary>
+        public readonly Bindable<string> DetailsText = new Bindable<string>();
+
         private readonly LocalisableString text;
 
+        private OsuTextFlowContainer textFlow = null!;
+        private ITextPart? detailsPart;
+
+        [Resolved]
+        private OverlayColourProvider colourProvider { get; set; } = null!;
+
         public SectionHeader(LocalisableString text)
         {
             this.text = text;
@@ -27,7 +40,7 @@ namespace osu.Game.Graphics.UserInterface
         }
 
         [BackgroundDependencyLoader]
-        private void load(OverlayColourProvider colourProvider)
+        private void load()
         {
             InternalChild = new FillFlowContainer
             {
@@ -37,7 +50,7 @@ namespace osu.Game.Graphics.UserInterface
                 Spacing = new Vector2(2),
                 Children = new Drawable[]
                 {
-                    new OsuTextFlowContainer(cp => cp.Font = OsuFont.Default.With(size: 16, weight: FontWeight.SemiBold))
+                    textFlow = new OsuTextFlowContainer(cp => cp.Font = OsuFont.Default.With(size: 16, weight: FontWeight.SemiBold))
                     {
                         Text = text,
                         RelativeSizeAxes = Axes.X,
@@ -51,5 +64,21 @@ namespace osu.Game.Graphics.UserInterface
                 }
             };
         }
+
+        protected override void LoadComplete()
+        {
+            base.LoadComplete();
+
+            DetailsText.BindValueChanged(updateDetails, true);
+        }
+
+        private void updateDetails(ValueChangedEvent<string> details)
+        {
+            if (detailsPart != null)
+                textFlow.RemovePart(detailsPart);
+
+            if (!string.IsNullOrEmpty(details.NewValue))
+                detailsPart = textFlow.AddText($" ({details.NewValue})", t => t.Colour = colourProvider.Highlight1);
+        }
     }
 }