Add FormValidationService and EventDefinitionService to dependency injection

Enhanced the application's service layer by adding FormValidationService and EventDefinitionService to the dependency injection container in Program.cs. Updated Create, Edit, and other relevant components to utilize these services for improved form validation and event processing functionality.

WebApp/Components/Features/Students/Create.razor

@@ -1,8 +1,13 @@
 @page "/students/create"
 @attribute [Authorize]
 @using WebApp.Components.Shared.Components
+@using MudBlazor
+@using WebApp.Services
+@using Microsoft.EntityFrameworkCore
 @inject AppDbContext Context
 @inject NavigationManager NavigationManager
+@inject ISnackbar Snackbar
+@inject FormValidationService ValidationService
 
 <PageHeader
     Title="Create"
@@ -10,10 +15,12 @@
     ShowBackButton="true"
     BackButtonUrl="@(ReturnUrl ?? "/students")" />
 
-<EditForm Model="Student" OnValidSubmit="OnValidSubmit" Enhance>
+<EditForm EditContext="@_editContext" OnValidSubmit="OnValidSubmit" OnInvalidSubmit="OnInvalidSubmit" Enhance>
     <FormChangeTracker @ref="_formChangeTracker" />
     <AntiforgeryToken />
     <DataAnnotationsValidator />
+    
+    <ValidationErrorDisplay Errors="_validationErrors" />
 
     <MudPaper Elevation="2" Class="pa-6">
         <MudText Typo="Typo.h5" Class="mb-4">Student Information</MudText>
@@ -53,14 +60,45 @@
     private Student Student { get; set; } = new() { TsaYear = 1 };
 
     private FormChangeTracker? _formChangeTracker;
+    private EditContext? _editContext;
+    private List<string> _validationErrors = new();
 
-    private void OnValidSubmit(EditContext context)
+    protected override void OnInitialized()
     {
-        _formChangeTracker?.AllowNavigation();
+        _editContext = new EditContext(Student);
+    }
 
-        Context.Students.Add(Student);
-        Context.SaveChanges();
-        NavigationManager.NavigateTo(ReturnUrl ?? "/students");
+    private void OnInvalidSubmit(EditContext editContext)
+    {
+        _validationErrors = ValidationService.HandleInvalidSubmit(editContext, Student, errors => _validationErrors = errors);
+        StateHasChanged();
+    }
+
+    private async Task OnValidSubmit()
+    {
+        _validationErrors.Clear();
+
+        try
+        {
+            Context.Students.Add(Student);
+            await Context.SaveChangesAsync();
+            
+            Snackbar.Add($"Student '{Student.FirstNameLastName}' created successfully.", Severity.Success);
+            _formChangeTracker?.AllowNavigation();
+            NavigationManager.NavigateTo(ReturnUrl ?? "/students");
+        }
+        catch (DbUpdateException ex)
+        {
+            ValidationService.HandleDbUpdateException(
+                ex,
+                "An error occurred while creating the student.",
+                "student",
+                "creating");
+        }
+        catch (Exception ex)
+        {
+            ValidationService.HandleException(ex);
+        }
     }
 
     private void HandleCancel()