fix reversed A/C chair mapping and update hot/cold on round end

CHAIRS mapping was {1:A, 2:B, 3:C} but the API's country field has
1=C and 3=A. Fixed the mapping in backend and both frontends, added a
startup migration to swap A↔C columns in existing DB data, corrected
multiIf SQL queries that hardcoded the wrong winner→column mapping,
and moved _save_round() to the ENDED status block so hot/cold stats
reflect the latest round immediately.

app/db.py

@@ -13,6 +13,7 @@ log = logging.getLogger(__name__)
 
 _client = None
 _lock = threading.Lock()
+_migrations_applied = False
 
 
 def get_client():
@@ -34,6 +35,34 @@ def get_client():
     return _client
 
 
+def run_migrations():
+    """Run one-time data migrations on startup."""
+    global _migrations_applied
+    if _migrations_applied:
+        return
+    client = get_client()
+    client.command(
+        "CREATE TABLE IF NOT EXISTS _migrations ("
+        "  name String, applied_at DateTime DEFAULT now()"
+        ") ENGINE = MergeTree() ORDER BY name"
+    )
+    result = client.query(
+        "SELECT count() FROM _migrations WHERE name = 'swap_ac_chairs'"
+    )
+    if result.result_rows[0][0] == 0:
+        log.info("Running migration: swap_ac_chairs")
+        client.command(
+            "ALTER TABLE games UPDATE "
+            "hand_a = hand_c, hand_c = hand_a, "
+            "bet_a = bet_c, bet_c = bet_a, "
+            "hand_type_a = hand_type_c, hand_type_c = hand_type_a "
+            "WHERE 1=1"
+        )
+        client.insert("_migrations", [["swap_ac_chairs"]], column_names=["name"])
+        log.info("Migration swap_ac_chairs applied")
+    _migrations_applied = True
+
+
 def _with_lock(fn):
     """Decorator to serialize all ClickHouse operations."""
     def wrapper(*args, **kwargs):
@@ -213,7 +242,7 @@ def get_win_distribution() -> dict:
         FROM (
             SELECT
                 bet_a, bet_b, bet_c,
-                multiIf(winner = 1, bet_a, winner = 2, bet_b, bet_c) AS winner_bet
+                multiIf(winner = 3, bet_a, winner = 2, bet_b, bet_c) AS winner_bet
             FROM games
             WHERE bet_a + bet_b + bet_c > 0
         )
@@ -414,7 +443,7 @@ def get_analytics(period: str = "all") -> dict:
         FROM (
             SELECT
                 bet_a, bet_b, bet_c,
-                multiIf(winner = 1, bet_a, winner = 2, bet_b, bet_c) AS winner_bet
+                multiIf(winner = 3, bet_a, winner = 2, bet_b, bet_c) AS winner_bet
             FROM games
             {game_where + ' AND' if game_where else 'WHERE'} bet_a + bet_b + bet_c > 0
         )
@@ -431,7 +460,7 @@ def get_analytics(period: str = "all") -> dict:
     hand_type_result = client.query(
         f"""
         SELECT hand_type, count() AS cnt FROM (
-            SELECT multiIf(winner = 1, hand_type_a, winner = 2, hand_type_b, hand_type_c) AS hand_type
+            SELECT multiIf(winner = 3, hand_type_a, winner = 2, hand_type_b, hand_type_c) AS hand_type
             FROM games
             {game_where}
         )