Fix KeyError: 'human' in gauntlet-9 CARDSETS

Added missing 'human' key to gauntlet-9 cardset configuration.
This was causing 500 errors when players tried to start gauntlet
games because the legal-check endpoint couldn't validate cards.

Error: KeyError: 'human' at app/routers_v2/cards.py:242
when checking CARDSETS[rarity_name]['human']

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

app/db_engine.py

@@ -116,6 +116,7 @@ CARDSETS = {
     "gauntlet-9": {
         "primary": [27],  # 2005
         "secondary": [24],  # 2025
+        "human": [x for x in range(1, 30)],
     },
 }