fix(accounting): store net PnL (payout - net_cost) in close_pnl, migrate Paxton record from gross to net

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

bot/data/db.py

@@ -173,7 +173,14 @@ class Database:
 
         resolution: 1.0 if YES resolved, 0.0 if NO resolved, None if unknown
         (legacy closes, inversion fixes). When resolution is provided, close_pnl
-        is computed in SQL so it matches the stored entry_price and shares exactly.
+        is computed in SQL per row as payout − net_cost — NET of fee, the single
+        PnL definition shared with PaperExecutor.close_position() (logs/Telegram):
+          BUY_YES: resolution * shares − net_cost
+          BUY_NO:  (1 − resolution) * shares − net_cost
+        paper.py aggregates payout − net_cost over these same open rows, so
+        SUM(close_pnl) per market equals the pnl it reports exactly. The
+        aggregate is intentionally NOT passed in as a parameter: writing it to
+        every row would double-count markets with more than one open trade.
         """
         async with self._pool.acquire() as conn:
             # $3 is cast on every use: Postgres cannot infer the parameter type
@@ -186,9 +193,9 @@ class Database:
                     resolution   = $3::double precision,
                     close_pnl    = CASE
                         WHEN $3::double precision IS NOT NULL AND direction = 'BUY_YES'
-                            THEN ($3::double precision - entry_price) * shares
+                            THEN ($3::double precision * shares) - net_cost
                         WHEN $3::double precision IS NOT NULL AND direction = 'BUY_NO'
-                            THEN ((1.0 - $3::double precision) - entry_price) * shares
+                            THEN ((1.0 - $3::double precision) * shares) - net_cost
                         ELSE NULL
                     END
                 WHERE market_id = $1 AND closed_at IS NULL

bot/data/schema.sql

@@ -113,9 +113,10 @@ CREATE INDEX IF NOT EXISTS idx_trades_closed ON trades(closed_at) WHERE closed_a
 -- Fix 3: market resolution and realized P&L per trade
 --
 -- resolution: 1.0 if YES resolved, 0.0 if NO resolved, NULL if not yet settled.
--- close_pnl:  realized P&L in USDC at close time.
---   BUY_YES: (resolution - entry_price) * shares
---   BUY_NO:  ((1 - resolution) - entry_price) * shares
+-- close_pnl:  realized P&L in USDC at close time — NET of fee (payout − net_cost),
+--   the same definition PaperExecutor.close_position() reports in logs/Telegram.
+--   BUY_YES: resolution * shares - net_cost
+--   BUY_NO:  (1 - resolution) * shares - net_cost
 --   NULL if closed without a known resolution (legacy closes, inversion fixes).
 -- ─────────────────────────────────────────────────────────────────────────────
 ALTER TABLE trades ADD COLUMN IF NOT EXISTS close_pnl  DOUBLE PRECISION;