Fix incorrect validation of circle size / key count

The big issue is that the range specified on the attribute was [1, 18]
which only makes sense in mania.

The small issue that while the range was checked, nothing decimal should
really be allowed for mania anyway.

A significant amount of this is kind of much-of-muchness because
`LegacyBeatmapDecoder` already does clamping on this:

https://github.com/ppy/osu/blob/834d63d1deacf0be0c4e76cd5d47cee136fbb49a/osu.Game/Beatmaps/Formats/LegacyBeatmapDecoder.cs#L113-L131

so the checks are kind of dead in practice, but I'd rather have them
not, what with users' propensity to try and break stuff and not have us
notice that it happened.

The game package bump here is significant because it exposes
`LegacyBeatmapDecoder.MAX_MANIA_KEY_COUNT`.

Author: bdach

osu.Server.BeatmapSubmission.Tests/BeatmapSubmissionControllerTest.cs

@@ -1636,7 +1636,7 @@ osu file format v14
             {
                 Assert.False(response.IsSuccessStatusCode);
 
-                Assert.Contains(playmode == 3 ? "The circle size of the beatmap is out of range." : "The key count of the beatmap is invalid.",
+                Assert.Contains(playmode == 3 ? "The key count of the beatmap is invalid." : "The circle size of the beatmap is out of range.",
                     (await response.Content.ReadFromJsonAsync<ErrorResponse>())!.Error);
             }
         }

osu.Server.BeatmapSubmission/Models/Database/osu_beatmap.cs

@@ -5,11 +5,12 @@
 
 using System.ComponentModel.DataAnnotations;
 using osu.Game.Beatmaps;
+using osu.Game.Beatmaps.Formats;
 using osu.Server.BeatmapSubmission.Models.Database.Validation;
 
 namespace osu.Server.BeatmapSubmission.Models.Database
 {
-    public class osu_beatmap
+    public class osu_beatmap : IValidatableObject
     {
         public uint beatmap_id { get; set; }
         public uint? beatmapset_id { get; set; }
@@ -45,7 +46,6 @@ public class osu_beatmap
         [Range(0.0, 10.0, ErrorMessage = "The drain rate of the beatmap is out of range.")]
         public float diff_drain { get; set; }
 
-        [Range(1.0, 18.0, ErrorMessage = "The circle size / key count of the beatmap is out of range.")]
         public float diff_size { get; set; }
 
         [Range(0.0, 10.0, ErrorMessage = "The overall difficulty of the beatmap is out of range.")]
@@ -69,5 +69,29 @@ public class osu_beatmap
         // deleted_at skipped on purpose
 
         public float bpm { get; set; }
+
+        public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
+        {
+            switch (playmode)
+            {
+                case 0:
+                case 1:
+                case 2:
+                {
+                    if (diff_size < 0 || diff_size > 10)
+                        yield return new ValidationResult("The circle size of the beatmap is out of range.");
+
+                    break;
+                }
+
+                case 3:
+                {
+                    if (diff_size != (int)diff_size || diff_size < 1 || diff_size > LegacyBeatmapDecoder.MAX_MANIA_KEY_COUNT)
+                        yield return new ValidationResult("The key count of the beatmap is invalid.");
+
+                    break;
+                }
+            }
+        }
     }
 }

osu.Server.BeatmapSubmission/osu.Server.BeatmapSubmission.csproj

@@ -19,11 +19,11 @@
         <PackageReference Include="DogStatsD-CSharp-Client" Version="8.0.0" />
         <PackageReference Include="Microsoft.AspNetCore.Authentication.JwtBearer" Version="8.0.10" />
         <PackageReference Include="Microsoft.AspNetCore.OpenApi" Version="8.0.10"/>
-        <PackageReference Include="ppy.osu.Game" Version="2025.304.0" />
-        <PackageReference Include="ppy.osu.Game.Rulesets.Catch" Version="2025.304.0" />
-        <PackageReference Include="ppy.osu.Game.Rulesets.Mania" Version="2025.304.0" />
-        <PackageReference Include="ppy.osu.Game.Rulesets.Osu" Version="2025.304.0" />
-        <PackageReference Include="ppy.osu.Game.Rulesets.Taiko" Version="2025.304.0" />
+        <PackageReference Include="ppy.osu.Game" Version="2025.420.0" />
+        <PackageReference Include="ppy.osu.Game.Rulesets.Catch" Version="2025.420.0" />
+        <PackageReference Include="ppy.osu.Game.Rulesets.Mania" Version="2025.420.0" />
+        <PackageReference Include="ppy.osu.Game.Rulesets.Osu" Version="2025.420.0" />
+        <PackageReference Include="ppy.osu.Game.Rulesets.Taiko" Version="2025.420.0" />
         <PackageReference Include="ppy.osu.Server.OsuQueueProcessor" Version="2024.1111.0" />
         <PackageReference Include="Sentry.AspNetCore" Version="5.2.0" />
         <PackageReference Include="Swashbuckle.AspNetCore" Version="7.3.1" />