fix: pin playoff card to its own gameNumber so the header doesn't tick forward after a final

series_state derives game_number from topSeedWins + bottomSeedWins + 1, which becomes the *next* game's number once the API advances seriesStatus post-final. The card for the just-finished game would then read "Game N+1 of 7". Prefer the raw gameNumber on the game payload, falling back to the derived value when it's missing.

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

app/playoff.py

@@ -92,10 +92,19 @@ def series_state(series_status):
     }
 
 
+def _game_number(game, state):
+    """This card's game number. Prefer the raw ``gameNumber`` field so we don't
+    drift forward once ``seriesStatus`` advances after the game ends."""
+    raw = game.get("gameNumber")
+    if isinstance(raw, int) and raw > 0:
+        return raw
+    return state["game_number"]
+
+
 def series_blurb(game):
     """One sentence of series context for a playoff card."""
     state = series_state(game.get("seriesStatus", {}))
-    g = state["game_number"]
+    g = _game_number(game, state)
     leader_name = _leader_name(game, state)
     trailer_name = _trailer_name(game, state)
 
@@ -137,7 +146,7 @@ def series_badges(game):
 def series_summary(game):
     """Short line rendered above the card, e.g. 'Game 2 of 7'."""
     state = series_state(game.get("seriesStatus", {}))
-    return f"Game {state['game_number']} of 7"
+    return f"Game {_game_number(game, state)} of 7"
 
 
 def is_pinned(game):