fix: db migration tab char corrupted, restore historical trades

db/db.go

@@ -113,6 +113,18 @@ func (d *DB) migrate() error {
 	if err != nil {
 		return err
 	}
+
+	// Migration v2: add per-exchange fee/pnl columns (idempotent)
+	for _, col := range []string{"pnl_long_usd", "pnl_short_usd", "fee_long_usd", "fee_short_usd"} {
+		var found int
+		d.QueryRow("SELECT COUNT(*) FROM pragma_table_info('trades') WHERE name=?", col).Scan(&found)
+		if found == 0 {
+			if _, err := d.Exec("ALTER TABLE trades ADD COLUMN " + col + " REAL"); err != nil {
+				log.Printf("[DB] Migration: add column %s: %v", col, err)
+			}
+		}
+	}
+
 	log.Printf("[DB] SQLite ready: %s", d.Path)
 	return nil
 }