Vest: a split day's next leg gives back the day's gain plus the limit

On a split day the next Vest leg's daily-loss room now adds the day's gain
still in the account to the bot's limit (floorRoom's `gain`), never past
Vest's own floor, and the leg sizes up for the same target hold (Dingo's
next eval leg: $455k -> $842k at 1.5 h, win 28% -> 56%). Other platforms
are unchanged: dllRoom still never widens on a green day.

The gain only widens a leg all but sure to close before Vest's 8 PM ET
reset (resetClearStop, held to the shortest leg the day may carve), and
none of a hand claim's profit counts. The last-stand margin is measured
against the limit, so a green day can't drop a leg's stop.

Around the reset: no new Vest position opens in the last 7 minutes, and
the guard re-fits every 15 s on fresh positions instead of one pass. An
account's positions share the next-day room (stops first, least at risk
first; locked-in profit counts), a hand-moved stop is fitted again, and a
close or profit-side stop that doesn't take is retried or closed.

The dashboard's next stop now reserves for the leg's notional, as fireLeg
does, so DXtrade labels read smaller (display only).

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

lib/platform-client.ts

@@ -125,12 +125,21 @@ export interface PlatformClient {
      * The equity the account may not fall below today, where the platform
      * states its daily-loss floor itself and moves it with the day's
      * transfers (Vest: reset balance × (1 − rate), lowered by a payout). The
-     * engine's room is then min(the stage's limit, balance − floor), so a
+     * engine's room is then what's left of the stage's limit (widened by
+     * dayGainForRoom), never more than balance − floor (floorRoom), so a
      * same-day payout that lowers the floor frees room to trade again. null =
      * the platform has one but it isn't known yet (hold); undefined = none
      * here (the engine falls back to dayStartBalance / realized P&L).
      */
     dailyLossFloor?(accountId: number): number | null | undefined;
+    /**
+     * With dailyLossFloor: how much of the day's gain a leg starting now, its
+     * take-profit `leg` away and its room `limit` before any gain, may add to
+     * its daily-loss room (floorRoom's `gain`) — the gain still in the account
+     * since the day's base, no more than keeps the leg all but sure to close
+     * before the platform's daily reset (resetClearStop).
+     */
+    dayGainForRoom?(accountId: number, o: { leg: number; limit: number }): number;
     /** Payouts made since the firm's last daily reset — what picks the stage
      *  of an account type whose stages reset each day. */
     sameDayClaims?(accountId: number): number;