Show the net prize as the jackpot instead of the gross pool

GET /rounds/current's jackpot_sats was the full pool (participant_count *
bet_amount_sats), which overstates what the winner actually receives once
the 30% commission is taken out at payout time. Apply the same 70% split
rounds/scheduler.py uses so the number shown during the round already
matches the real payout, without surfacing the fee itself in the UI/docs.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app/api/routes/rounds.py

@@ -52,6 +52,12 @@ async def current_round(request: Request, session: AsyncSession = Depends(get_se
     closes_at = opened_at + timedelta(seconds=config.round_duration_seconds)
     await session.commit()
 
+    # Shown to players as "jackpot": the winner's 70% share of the pool (same
+    # split rounds/scheduler.py applies at payout time), not the full pool —
+    # what's displayed should match what the winner actually receives.
+    pool_amount_sats = participant_count * config.bet_amount_sats
+    jackpot_sats = pool_amount_sats * 70 // 100
+
     return CurrentRoundResponse(
         server_time=datetime.now(timezone.utc).isoformat(),
         round_id=round_.id,
@@ -60,7 +66,7 @@ async def current_round(request: Request, session: AsyncSession = Depends(get_se
         closes_at=closes_at.isoformat(),
         participant_count=participant_count,
         bet_amount_sats=config.bet_amount_sats,
-        jackpot_sats=participant_count * config.bet_amount_sats,
+        jackpot_sats=jackpot_sats,
         draw_animation_seconds=config.draw_animation_seconds,
         winner_user_id=round_.winner_user_id,
         winner_amount_sats=round_.winner_amount_sats,

docs/guida-utente.md

@@ -29,8 +29,7 @@ Dopo l'accesso vedi, in ordine:
    - **timer** che conta alla rovescia il tempo rimanente prima della
      chiusura del round
    - **giocatori**: quanti hanno già piazzato una bet in questo round
-   - **jackpot**: il totale in PLM che verrà distribuito (70% al vincitore,
-     30% in fee)
+   - **jackpot**: quanto riceverà chi vince questo round
 3. **Tab di navigazione** con quattro sezioni:
 
 ### Estrazione del vincitore