Trump card: draw from the stack, no trump for wizards and jesters

- Deal the hands from the shuffled stack and draw the trump card from it,
  so the trump card is in nobody's hand and cannot be played
- A wizard or jester as trump card means no trump suit (previously a
  wizard let the dealer choose); remove the trump selection phase, the
  ChooseTrump action, the trump picker UI and the AI trump actions
- Completed tricks carry their round's trump card, so the table keeps
  showing the matching trump card while the last trick of a round is
  displayed
- Card corners are no longer rotated, so 6 and 9 cannot be confused
- Trump label explains why there is no trump (wizard, jester, last round)
- Tests: trump card never dealt, special cards give no trump, tricks keep
  their trump card

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

wizard_server/game_logic/wizard_game/rules.py

@@ -28,6 +28,17 @@ def validate_player_count(num_players: int) -> None:
         )
 
 
+def trump_suit(trump_card: Card | None) -> Suit | None:
+    """The trump suit defined by the turned up trump card.
+
+    Only a number card defines a trump suit. A wizard, a jester or no trump
+    card at all (last round) means the round is played without trump.
+    """
+    if trump_card is None or not trump_card.is_number:
+        return None
+    return trump_card.suit
+
+
 def lead_suit(trick: Sequence[Card]) -> Suit | None:
     """The suit that has to be followed in a trick.