add xmldoc comments

web/backend/Database/Database.Seed/Program.cs

@@ -3,6 +3,20 @@ using DbUp;
 using System.Reflection;
 using Database.Seed;
 
+// Entry point for the database seeding utility. Connects to the target database
+// (retrying on transient failures), then runs each registered ISeeder in order to
+// populate location and user data.
+
+/// <summary>
+/// Builds a SQL Server connection string from the <c>DB_SERVER</c>, <c>DB_NAME</c>,
+/// <c>DB_USER</c>, <c>DB_PASSWORD</c>, and <c>DB_TRUST_SERVER_CERTIFICATE</c>
+/// environment variables.
+/// </summary>
+/// <returns>A fully built SQL Server connection string.</returns>
+/// <exception cref="InvalidOperationException">
+/// Thrown when <c>DB_SERVER</c>, <c>DB_NAME</c>, <c>DB_USER</c>, or <c>DB_PASSWORD</c>
+/// is not set.
+/// </exception>
 string BuildConnectionString()
 {
     var server = Environment.GetEnvironmentVariable("DB_SERVER")