Update database handling code (#247)

web/backend/Database/Database.Migrations/MasterSqlConnectionFactory.cs

@@ -0,0 +1,37 @@
+using Database.Connection;
+using Microsoft.Data.SqlClient;
+using Microsoft.Extensions.Configuration;
+
+namespace Database.Migrations;
+
+/// <summary>
+///     <see cref="ISqlConnectionFactory" /> implementation that connects to the <c>master</c> database,
+///     used for create and drop operations on the target application database.
+/// </summary>
+public class MasterSqlConnectionFactory(IConfiguration configuration) : ISqlConnectionFactory
+{
+    /// <inheritdoc />
+    public string ConnectionString
+    {
+        get
+        {
+            if (
+                SqlConnectionStringHelper.TryGetMasterConnectionString(
+                    configuration,
+                    out var connectionString
+                )
+            )
+                return connectionString;
+
+            throw new InvalidOperationException(
+                "Database connection string not configured. Set DB_SERVER, DB_USER, DB_PASSWORD env vars."
+            );
+        }
+    }
+
+    /// <inheritdoc />
+    public SqlConnection CreateConnection()
+    {
+        return new SqlConnection(ConnectionString);
+    }
+}