DXtrade sizing: volatility only (12h default hold); fees and every-day only for DXtrade

The symbol map's fixed notional per contract is gone: every DXtrade leg is
sized from the instrument's recent volatility for the firm's target hold
(blank = 12 h), and a candidate without a volatility isn't picked. Percent
commission and every-day trading are ignored on non-DXtrade firms, which keep
measured per-contract fees and the CME calendar.

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

lib/master-protocol.ts

@@ -228,13 +228,12 @@ export function isFirmPlatform(value: unknown): value is FirmPlatform {
     return typeof value === 'string' && (FIRM_PLATFORMS as readonly string[]).includes(value);
 }
 
-/** One symbol a DXTrade firm may trade for a CME root. */
+/** One symbol a DXTrade firm may trade for a CME root. Position size comes
+ *  from volatility and the firm's target hold, never from the map (an older
+ *  master's notionalPerContract is ignored). */
 export interface SymbolMapCandidate {
     /** The platform's symbol, e.g. "BTC/USD". */
     symbol: string;
-    /** Fixed sizing: notional per $1,000 of leg (like futures' one contract
-     *  per $1,000). Used when volatility sizing is off or can't run. */
-    notionalPerContract: number;
     /** Per-side commission % for this symbol; absent = the firm's. */
     commissionPct?: number;
 }
@@ -263,8 +262,8 @@ export interface CatalogFirm {
     tradesEveryDay?: boolean;
     /** DXTrade: which symbols each CME root may trade as. */
     symbolMap?: SymbolMap;
-    /** DXTrade volatility sizing: aim each leg's expected hold at this many
-     *  hours (0 = fixed sizing from the symbol map). */
+    /** DXTrade sizing: aim each leg's expected hold at this many hours
+     *  (0 = DEFAULT_TARGET_HOLD_HOURS, 12). */
     targetHoldHours?: number;
     /** Overnight financing the firm charges, % of notional per day (0 = none). */
     financingPctPerDay?: number;