Report each symbol's next-leg stats to the master; drop per-symbol commission

- lib/leg-estimate: an account's next leg sized on every surveyed
  candidate (planLegSize, ranked by rankForTarget) — notional, its
  multiple of the account and the broker's maximum, expected hold, cost
  and win chance. The dashboard's hold estimate and the reporter share it.
- The reporter sends it per DXtrade firm as symbolStats, for one live
  account from the largest prefix group with a leg left to trade.
- The symbol map's per-symbol commission is gone: the firm's applies.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

lib/firm-catalog.ts

@@ -156,9 +156,7 @@ function sanitizeSymbolMap(raw: unknown): SymbolMap {
             if (typeof c !== 'object' || c === null) return [];
             const cand = c as Record<string, unknown>;
             if (typeof cand.symbol !== 'string' || !cand.symbol || cand.symbol.includes('|')) return [];
-            const pct = typeof cand.commissionPct === 'number' && Number.isFinite(cand.commissionPct) && cand.commissionPct >= 0
-                ? cand.commissionPct : undefined;
-            return [{ symbol: cand.symbol, ...(pct !== undefined ? { commissionPct: pct } : {}) }];
+            return [{ symbol: cand.symbol }];
         });
         if (candidates.length > 0) map[root.toUpperCase()] = candidates;
     }