Report per-account-type days-traded histograms to the master

Adds daysHist ({daysTraded: accountCount}) to AccountTypeStats, computed
from the same combined-day view the trade path uses and covering every
live account including ones mid-trade. Feeds the master's payout
calendar; an older master simply ignores the field.

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

lib/master-protocol.ts

@@ -22,6 +22,10 @@ export interface AccountTypeStats {
     targetHit?: number;
     partial?: number;
     loss?: number;
+    /** Live accounts by trading days completed toward the current target:
+     *  {daysTraded: accountCount}. Feeds the master's payout calendar.
+     *  Optional so an older master simply ignores it. */
+    daysHist?: Record<number, number>;
 }
 
 export interface FirmStats {

lib/reporter.ts

@@ -80,6 +80,18 @@ function collectFirmStats() {
             totalAccounts++;
             slice.totalAccounts++;
 
+            // Same combined-day view as the trade path: for a combining firm,
+            // "today" spans the holiday stretch. Computed for every live
+            // account — including ones mid-trade — so the days-traded
+            // histogram below covers the whole slice.
+            const combined = cfg ? combineCmeSessions(
+                cfg.combineCmeHolidays, client.dailyPnL[acc.id] ?? [], currentTradeDateCT(), cash.realizedPnL,
+            ) : null;
+            if (combined) {
+                const hist = (slice.daysHist ??= {});
+                hist[combined.daysTraded] = (hist[combined.daysTraded] ?? 0) + 1;
+            }
+
             if (client.positions[acc.id]) {
                 inTrade++;
                 accountsTraded++;
@@ -100,12 +112,7 @@ function collectFirmStats() {
             }
 
             // Check if target was hit today
-            if (cfg) {
+            if (cfg && combined) {
-                // Same combined-day view as the trade path: for a combining
-                // firm, "today" spans the holiday stretch.
-                const combined = combineCmeSessions(
-                    cfg.combineCmeHolidays, client.dailyPnL[acc.id] ?? [], currentTradeDateCT(), cash.realizedPnL,
-                );
                 const equityProfit = cash.amount - cfg.accountSize;
                 const plan = computeDayPlan(
                     acc.id, combined.tradeDate, cfg.profitTarget, cfg.consistency,