feat(clubSettings): enhance club settings with myTischtennis integration

- Added new fields for myTischtennis club ID, federation nickname, and auto-fetch rankings in the club settings.
- Updated the backend to handle the new settings in the updateClubSettings method.
- Implemented automatic ranking updates for clubs based on the new settings in the autoUpdateRatingsService.
- Enhanced the frontend to support the new settings, including validation and user interface updates for better user experience.

backend/migrations/20260315_add_club_rankings_settings.sql

@@ -0,0 +1,10 @@
+-- Migration: Add myTischtennis rankings settings to clubs table
+-- Enables per-club configuration of TTR/QTTR rankings fetch (club ID, federation, enable flag)
+
+ALTER TABLE clubs
+  ADD COLUMN IF NOT EXISTS my_tischtennis_club_id VARCHAR(50) NULL
+    COMMENT 'myTischtennis club number for rankings (e.g. 43030)',
+  ADD COLUMN IF NOT EXISTS my_tischtennis_fed_nickname VARCHAR(50) NULL
+    COMMENT 'Federation short name for rankings (e.g. HeTTV)',
+  ADD COLUMN IF NOT EXISTS auto_fetch_rankings BOOLEAN NOT NULL DEFAULT FALSE
+    COMMENT 'Enable automatic TTR/QTTR rankings fetch for this club';