feat(tournament): enhance external participant management with email and address fields

- Added email and address fields to the external participant model, allowing for more comprehensive participant information.
- Updated the tournament service and controller to handle the new fields when adding external participants.
- Modified frontend components to include input fields for email and address, improving user experience and data collection.
- Updated localization strings to support the new fields, ensuring clarity in the user interface.

backend/migrations/20260130_add_email_address_to_external_participant.sql

@@ -0,0 +1,6 @@
+-- E-Mail und Adresse für externe Teilnehmer (für Weitermeldung)
+-- Die Felder werden verschlüsselt gespeichert (siehe Model)
+
+ALTER TABLE `external_tournament_participant`
+  ADD COLUMN `email` VARCHAR(500) NULL AFTER `club`,
+  ADD COLUMN `address` TEXT NULL AFTER `email`;