fix: ensure Telegram is always primary in identity links

When a Discord user linked Telegram via the Telegram Login Widget,
LinkIdentityAsync incorrectly made Discord primary and Telegram
secondary. This broke access to all Telegram groups/sessions because
ResolveEffectivePlayerIdAsync returned the (empty) Discord primary.

- In /auth/telegram callback, swap LinkIdentityAsync args so Telegram
  is always treated as the current (primary) account.
- Add V022 migration to reverse any existing incorrectly-oriented
  player_links where Discord is primary and Telegram is secondary.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/GmRelay.Bot/Migrations/V022__fix_discord_telegram_links.sql

@@ -0,0 +1,16 @@
+-- =============================================================
+-- V022: Fix incorrectly oriented player_links for Discord↔Telegram
+-- =============================================================
+-- Scope: Reverse player_links where Discord was incorrectly made primary
+-- and Telegram secondary. Telegram (with historical group/session data)
+-- must always be the primary account.
+-- =============================================================
+
+UPDATE player_links pl
+SET primary_player_id   = pl.secondary_player_id,
+    secondary_player_id = pl.primary_player_id
+FROM players p1, players p2
+WHERE pl.primary_player_id = p1.id
+  AND pl.secondary_player_id = p2.id
+  AND p1.platform = 'Discord'
+  AND p2.platform = 'Telegram';