Add configuration type binding and implement database connection, disable NativeAOT.

Add: binding setting file items to `AppSettings` class so to provide DI access as `IOptions<OptixServeSettings>`.

Add: EF Core and DbContext to access database in services. This results in disabling NativeAOT due to poor supports for *pre-compiled query*, however many design are optimized for AOT for later re-adoption.

Add: `DesignTimeDbContextFactory` to support EF Core migrations in NativeAOT. (Kept for re-enabling AOT.)

Add: `DbInitializer` for ensuring database connecting in startup.

Add: `ConfigurationHelper.CreateDefaultBuilder()` to read configuration files in default locations. Note this method is currently ONLY used by `DesignTimeDbContextFactory`. Refactor is expected.

Add: `CommonErrorDto` for simple error message.

Add: `VersionEndpoint` ONLY for debugging and testing purpose. Verylikely to be removed in the future.

Other: many utilities and fixes easy to understand.

Note: EF Core migrations are excluded in the early development. Not expected to be added in version control before v1.0 beta.

OptixServe.Api/Utilites/DatabaseHelper.cs

@@ -0,0 +1,34 @@
+using Microsoft.EntityFrameworkCore;
+using OptixServe.Api.Configuration;
+using OptixServe.Core.Data;
+
+namespace OptixServe.Api.Utilites;
+
+public static class DatabaseHelper
+{
+    public static string BuildConnectionString(DatabaseSettings dbSettings)
+    {
+        return dbSettings.Type switch
+        {
+            DatabaseType.Sqlite => $"Data Source={dbSettings.Host ?? "optixserve.db"}",
+            DatabaseType.MySQL => throw new NotSupportedException("MySQL connection is not yet implemented"),
+            _ => throw new NotSupportedException($"Database type {dbSettings.Type} is not supported")
+        };
+    }
+
+    public static void ConfigureDbContext(DbContextOptionsBuilder options, DatabaseSettings dbSettings)
+    {
+        if (dbSettings?.Type == DatabaseType.Sqlite)
+        {
+            var dbPath = dbSettings.Host ?? "optixserve.db";
+            var connectionString = $"Data Source={dbPath}";
+
+            options.UseSqlite(connectionString, b => b.MigrationsAssembly("OptixServe.Api"));
+
+        }
+        else
+        {
+            throw new NotImplementedException("Only SQLite database is currently supported");
+        }
+    }
+}

OptixServe.Api/Utilites/DesignTimeDbContextFactory.cs

@@ -0,0 +1,20 @@
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Design;
+using OptixServe.Api.Configuration;
+using OptixServe.Core.Data;
+
+namespace OptixServe.Api.Utilites;
+
+public class DesignTimeDbContextFactory : IDesignTimeDbContextFactory<AppDbContext>
+{
+    public AppDbContext CreateDbContext(string[] args)
+    {
+        var configuration = ConfigurationHelper.CreateDefaultBuilder().Build();
+
+        var dbSettings = configuration.GetSection("OptixServe:Database").Get<DatabaseSettings>()!;
+        var optionsBuilder = new DbContextOptionsBuilder<AppDbContext>();
+        DatabaseHelper.ConfigureDbContext(optionsBuilder, dbSettings);
+
+        return new AppDbContext(optionsBuilder.Options);
+    }
+}