Allow custom admin username and email during install

The installer now prompts for and validates a custom admin username and email, updating migrations and SQL placeholders accordingly. Login now accepts either username or email, and the login form and installer views have been updated to reflect these changes. Additional logging and migration handling improvements were made for better installation and authentication workflows.

database/migrations/002_create_users_table.sql

@@ -14,9 +14,9 @@ CREATE TABLE IF NOT EXISTS users (
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
 
 -- Insert default admin user
--- Password is randomly generated during installation and displayed in output
--- Hash placeholder will be replaced by web installer
+-- Credentials are set during installation and displayed in output
+-- Placeholders will be replaced by web installer
 INSERT INTO users (username, password, email, full_name, is_active) VALUES
-('admin', '{{ADMIN_PASSWORD_HASH}}', 'admin@domainmonitor.local', 'Administrator', 1)
+('{{ADMIN_USERNAME}}', '{{ADMIN_PASSWORD_HASH}}', '{{ADMIN_EMAIL}}', 'Administrator', 1)
 ON DUPLICATE KEY UPDATE username=username;