fix(backend): Fix LINQ translation issue in UserTenantRoleRepository

Fixed EF Core LINQ query translation error that caused 500 errors in Login and Refresh Token endpoints.

Problem:
- UserTenantRoleRepository was using `.Value` property accessor on value objects (UserId, TenantId) in LINQ queries
- EF Core could not translate expressions like `utr.UserId.Value == userId` to SQL
- This caused System.InvalidOperationException with message "The LINQ expression could not be translated"
- Resulted in 500 Internal Server Error for Login and Refresh Token endpoints

Solution:
- Create value object instances (UserId.Create(), TenantId.Create()) before query
- Compare value objects directly instead of accessing .Value property
- EF Core can translate value object comparison due to HasConversion configuration
- Removed .Include(utr => utr.User) since User navigation is ignored in EF config

Impact:
- Login endpoint now works correctly (200 OK)
- Refresh Token endpoint now works correctly (200 OK)
- RBAC role assignment and retrieval working properly
- Resolves BUG-003 and BUG-004 from QA test report

Test Results:
- Before fix: 57% pass rate (8/14 tests)
- After fix: ~79% pass rate (11/14 tests) - core functionality restored
- Diagnostic test: All critical endpoints (Register, Login, Refresh) passing

Files Changed:
- UserTenantRoleRepository.cs: Fixed all three query methods (GetByUserAndTenantAsync, GetByUserAsync, GetByTenantAsync)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

colaflow-api/src/Modules/Identity/ColaFlow.Modules.Identity.Infrastructure/Persistence/Repositories/UserTenantRoleRepository.cs

@@ -1,4 +1,5 @@
 using ColaFlow.Modules.Identity.Domain.Aggregates.Users;
+using ColaFlow.Modules.Identity.Domain.Aggregates.Tenants;
 using ColaFlow.Modules.Identity.Domain.Repositories;
 using Microsoft.EntityFrameworkCore;
 
@@ -18,9 +19,13 @@ public class UserTenantRoleRepository : IUserTenantRoleRepository
         Guid tenantId,
         CancellationToken cancellationToken = default)
     {
+        // Create value objects to avoid LINQ translation issues with .Value property
+        var userIdVO = UserId.Create(userId);
+        var tenantIdVO = TenantId.Create(tenantId);
+
         return await _context.UserTenantRoles
             .FirstOrDefaultAsync(
-                utr => utr.UserId.Value == userId && utr.TenantId.Value == tenantId,
+                utr => utr.UserId == userIdVO && utr.TenantId == tenantIdVO,
                 cancellationToken);
     }
 
@@ -28,8 +33,11 @@ public class UserTenantRoleRepository : IUserTenantRoleRepository
         Guid userId,
         CancellationToken cancellationToken = default)
     {
+        // Create value object to avoid LINQ translation issues with .Value property
+        var userIdVO = UserId.Create(userId);
+
         return await _context.UserTenantRoles
-            .Where(utr => utr.UserId.Value == userId)
+            .Where(utr => utr.UserId == userIdVO)
             .ToListAsync(cancellationToken);
     }
 
@@ -37,9 +45,12 @@ public class UserTenantRoleRepository : IUserTenantRoleRepository
         Guid tenantId,
         CancellationToken cancellationToken = default)
     {
+        // Create value object to avoid LINQ translation issues with .Value property
+        var tenantIdVO = TenantId.Create(tenantId);
+
         return await _context.UserTenantRoles
-            .Where(utr => utr.TenantId.Value == tenantId)
-            .Include(utr => utr.User) // Include user details for tenant management
+            .Where(utr => utr.TenantId == tenantIdVO)
+            // Note: User navigation is ignored in EF config, so Include is skipped
             .ToListAsync(cancellationToken);
     }