Change last year placing from integer to string in tournament overlay

[ILW8]

This PR changes the "Last year's placing" field from an integer to a string, matching what is currently used for the "Seed" field. This also slightly adjusts the textboxes in the team editor screen to better fit the textbox which replaced the last year placing slider.

Tournaments often show teams' last year placing as a range instead of a simple number as a result of bracket elimination. For example, in OWC2025, Japan was eliminated in the lower bracket round 2 along with 8 other teams, which gives them a placement of 17th-24th.

Team editor screen:

Before
After

Seeding screen:

With seed and placement	No seed nor placing

[bdach]

I would much rather do something like

diff --git a/osu.Game.Tournament/Models/TournamentTeam.cs b/osu.Game.Tournament/Models/TournamentTeam.cs
index ab353d771a..4368c2fda8 100644
--- a/osu.Game.Tournament/Models/TournamentTeam.cs
+++ b/osu.Game.Tournament/Models/TournamentTeam.cs
@@ -2,6 +2,7 @@
 // See the LICENCE file in the repository root for full licence text.
 
 using System;
+using System.Diagnostics;
 using System.Linq;
 using Newtonsoft.Json;
 using osu.Framework.Bindables;
@@ -49,25 +50,9 @@ public double AverageRank
 
         public Bindable<string> Seed = new Bindable<string>(string.Empty);
 
-        [JsonIgnore]
-        public Bindable<string> LastYearPlacing = new Bindable<string>("N/A");
-
-        /// <summary>
-        /// Previously, a value of 0 was meant to indicate "no placement last year".
-        /// This will convert the number 0 from an old bracket.json file back to the "N/A" string (new default).
-        /// </summary>
-        [JsonProperty("LastYearPlacing")]
-        private object lastYearPlacing
-        {
-            get => LastYearPlacing.Value;
-            set
-            {
-                if (value is long oldValue && oldValue == 0)
-                    LastYearPlacing.Value = LastYearPlacing.Default;
-                else
-                    LastYearPlacing.Value = value.ToString() ?? LastYearPlacing.Default;
-            }
-        }
+        [JsonProperty]
+        [JsonConverter(typeof(LastYearPlacingConverter))]
+        public Bindable<string> LastYearPlacing = new Bindable<string>(@"N/A");
 
         [JsonProperty]
         public BindableList<TournamentUser> Players { get; } = new BindableList<TournamentUser>();
@@ -90,5 +75,37 @@ public TournamentTeam()
         }
 
         public override string ToString() => FullName.Value ?? Acronym.Value;
+
+        public class LastYearPlacingConverter : JsonConverter
+        {
+            public override bool CanConvert(Type objectType) => objectType == typeof(Bindable<string>);
+
+            public override void WriteJson(JsonWriter writer, object? value, JsonSerializer serializer)
+                => serializer.Serialize(writer, ((Bindable<string>)value!).Value);
+
+            public override object ReadJson(JsonReader reader, Type objectType, object? existingValue, JsonSerializer serializer)
+            {
+                var lastYearPlacing = existingValue as Bindable<string>;
+                Debug.Assert(lastYearPlacing != null);
+
+                switch (reader.TokenType)
+                {
+                    case JsonToken.String:
+                        lastYearPlacing.Value = (string?)reader.Value ?? lastYearPlacing.Default;
+                        break;
+
+                    case JsonToken.Integer:
+                        long value = (long)reader.Value!;
+                        lastYearPlacing.Value = value > 0 ? $@"#{value}" : lastYearPlacing.Default;
+                        break;
+
+                    default:
+                        reader.Read();
+                        break;
+                }
+
+                return lastYearPlacing;
+            }
+        }
     }
 }

than do this. I have much unresolved trauma from doing "setter tricks" like this that later just absolutely die on something very stupid and require even stupider things to unknot.

[ILW8]

Fair enough, in the first place I was debating whether to include the conversion at all since seeding is usually a one-off thing for a tournament anyway.

I've applied this patch, but I'm tempted to just remove the conversion completely at this point.