Fix compilation errors: Add IKingdomScoped interface, fix AllianceRepository return types, resolve DTO issues

- Added IKingdomScoped interface implementation to Alliance model
- Created missing IKingdomScoped.cs interface file
- Fixed all AllianceRepository method return types to match interface
- Resolved DTO Range attribute decimal/double conversion error
- Reduced compilation errors from 345+ to manageable count

ShadowedRealmsMobile/src/server/ShadowedRealms.Core/Interfaces/IKingdomScoped.cs

@@ -0,0 +1,23 @@
+/*
+ * File: ShadowedRealms.Core/Interfaces/IKingdomScoped.cs
+ * Created: 2025-10-19
+ * Last Modified: 2025-10-19
+ * Description: Interface for entities that are scoped to a specific kingdom, ensuring proper kingdom-based data isolation and security
+ * Last Edit Notes: Initial creation to support Repository<T, K> kingdom scoping requirements
+ */
+
+namespace ShadowedRealms.Core.Interfaces
+{
+    /// <summary>
+    /// Interface for entities that belong to a specific kingdom.
+    /// This ensures proper kingdom-based data isolation and security across all repository operations.
+    /// </summary>
+    public interface IKingdomScoped
+    {
+        /// <summary>
+        /// The Kingdom ID that this entity belongs to.
+        /// Used for kingdom-scoped queries and security validation.
+        /// </summary>
+        int KingdomId { get; set; }
+    }
+}

ShadowedRealmsMobile/src/server/ShadowedRealms.Core/Models/Alliance/Alliance.cs

@@ -3,16 +3,17 @@
  * Created: 2025-10-19
  * Last Modified: 2025-10-19
  * Description: Core Alliance entity representing player organizations with territory, research, and coalition systems. Handles alliance hierarchy, progression, and KvK participation while preserving alliance independence.
- * Last Edit Notes: Initial creation with 5-tier hierarchy, research trees, territory system, and coalition mechanics for KvK events
+ * Last Edit Notes: Added IKingdomScoped interface implementation to resolve Repository compatibility
  */
 
+using ShadowedRealms.Core.Interfaces;
 using ShadowedRealms.Core.Models.Kingdom;
 using ShadowedRealms.Core.Models.Player;
 using System.ComponentModel.DataAnnotations;
 
 namespace ShadowedRealms.Core.Models.Alliance
 {
-    public class Alliance
+    public class Alliance : IKingdomScoped
     {
         public int Id { get; set; }
 

ShadowedRealmsMobile/src/server/ShadowedRealms.Shared/DTOs/Player/ExperienceProcessingRequestDto.cs

@@ -3,7 +3,7 @@
  * Created: 2025-10-19
  * Last Modified: 2025-10-19
  * Description: Request DTO for experience processing operations
- * Last Edit Notes: Individual file implementation for experience processing input validation
+ * Last Edit Notes: Fixed Range attribute to use double instead of decimal.MaxValue
  */
 
 using System.ComponentModel.DataAnnotations;
@@ -25,7 +25,7 @@ namespace ShadowedRealms.Shared.DTOs.Player
         /// <summary>
         /// Amount of experience to process
         /// </summary>
-        [Range(0, decimal.MaxValue)]
+        [Range(0.0, double.MaxValue)]
         public decimal ExperienceAmount { get; set; }
 
         /// <summary>