feat: Shift quality definition limits management to the backend

This update moves the minimum, maximum, and preferred quality limits to
the backend, accessible via the new `/qualitydefinition/limits`
endpoint. This change improves support for unofficial Sonarr API clients
and enables a more flexible frontend.

src/NzbDrone.Core/Qualities/QualityDefinitionLimits.cs

@@ -0,0 +1,11 @@
+using System.Diagnostics.CodeAnalysis;
+
+namespace NzbDrone.Core.Qualities;
+
+[SuppressMessage("Performance", "CA1822:Mark members as static", Justification =
+    "Serializable properties of a DTO")]
+public record QualityDefinitionLimits
+{
+    public int MinLimit => 0;
+    public int MaxLimit => 1000;
+}

src/NzbDrone.Core/Qualities/QualityDefinitionService.cs

@@ -17,6 +17,7 @@ namespace NzbDrone.Core.Qualities
         List<QualityDefinition> All();
         QualityDefinition GetById(int id);
         QualityDefinition Get(Quality quality);
+        QualityDefinitionLimits GetLimits();
     }
 
     public class QualityDefinitionService : IQualityDefinitionService, IExecute<ResetQualityDefinitionsCommand>, IHandle<ApplicationStartedEvent>
@@ -64,6 +65,11 @@ namespace NzbDrone.Core.Qualities
             return GetAll()[quality];
         }
 
+        public QualityDefinitionLimits GetLimits()
+        {
+            return new QualityDefinitionLimits();
+        }
+
         private void InsertMissingDefinitions()
         {
             var insertList = new List<QualityDefinition>();

src/Sonarr.Api.V3/Qualities/QualityDefinitionController.cs

@@ -55,6 +55,12 @@ namespace Sonarr.Api.V3.Qualities
                 .ToResource());
         }
 
+        [HttpGet("limits")]
+        public ActionResult<QualityDefinitionLimits> GetLimits()
+        {
+            return Ok(_qualityDefinitionService.GetLimits());
+        }
+
         [NonAction]
         public void Handle(CommandExecutedEvent message)
         {