整合 Entity Framework Core 與 Pomelo MySQL

此次變更新增必要的命名空間，設置資料庫連接字串，並透過 `AddDbContext` 註冊 `ApplicationDbContext`。配置 MySQL 伺服器版本及相關選項，包括字符集和重試機制。根據開發環境啟用詳細錯誤和敏感數據日誌記錄，並添加控制台日誌記錄的過濾器。最後，應用程式被構建並運行。

Program.cs

@@ -0,0 +1,46 @@
+using System;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Diagnostics;
+using Microsoft.Extensions.Logging;
+using Pomelo.EntityFrameworkCore.MySql.Infrastructure;
+
+var builder = WebApplication.CreateBuilder(args);
+
+// 讀取連線字串
+var connectionString = builder.Configuration.GetConnectionString("DefaultConnection")
+    ?? throw new InvalidOperationException("Connection string 'DefaultConnection' not found.");
+
+// EF Core + Pomelo MySQL 註冊
+builder.Services.AddDbContext<ApplicationDbContext>(options =>
+{
+    var serverVersion = new MariaDbServerVersion(new Version(10, 6, 0));
+
+    options.UseMySql(connectionString, serverVersion, mySqlOptions =>
+    {
+        // 字元集設定
+        mySqlOptions.CharSet(CharSet.Utf8Mb4);
+        mySqlOptions.CharSetBehavior(CharSetBehavior.AppendToAllColumns);
+        // 可選：重試策略
+        mySqlOptions.EnableRetryOnFailure(5, TimeSpan.FromSeconds(10), null);
+    });
+
+    // 開發環境顯示更詳細的資料庫日誌
+    if (builder.Environment.IsDevelopment())
+    {
+        options.EnableDetailedErrors();
+        options.EnableSensitiveDataLogging();
+        options.LogTo(Console.WriteLine, LogLevel.Information, DbContextLoggerOptions.DefaultWithLocalTime);
+    }
+});
+
+// Logging（只在開發環境加強輸出 EF Core 訊息）
+if (builder.Environment.IsDevelopment())
+{
+    builder.Logging.AddConsole()
+        .AddFilter("Microsoft.EntityFrameworkCore.Database.Command", LogLevel.Information)
+        .AddFilter("Microsoft.EntityFrameworkCore.Infrastructure", LogLevel.Information);
+}
+
+var app = builder.Build();
+
+app.Run();