fix: preserve rounded margin calls for high-value fractional market entries

[luisleo526]

Rounded-money margin calls were skipped when a fractional minimum lot became worth at least one account-currency unit, including BTC above 100,000 USDT. The engine now retains the confirmed rounding check for ordinary, fee-free market-opened long positions with fractional lots, including immediate opening valuation. Exact fill provenance keeps priced and raw orders on their existing paths.

Validated on engine fb97ebd5fb8bc2038c19b74c6e741dc422756403 with codegen 3fd97fe28abd7b191cb376d9f5db4e056fcfae4b:

• Cloud Run measured all 4,190 probes in 72/72 cases. Mazi and QuantitativeAlpha on BTCUSDT move from strong to excellent; the other 4,188 canonical results are unchanged. Zero regressions, errors or coverage gaps. Result: 4,163 excellent / 27 strong / zero moderate.
• All 144 Mazi and 4,006 QuantitativeAlpha entry/exit rows match TradingView on side, time, price and quantity. The missing margin calls and subsequent position quantities are restored.
• Gate pineforge-pr-gate-88zx5: PASS, target score +2, and zero regressions or tolerated exceptions across 704 hard probes.
• Fresh build and 213/213 tests passed. Covered TradingView capital controls verify both opening and later path-point events. Tests also preserve priced/raw orders, fees, slippage, FX, point values, integer/continuous lots and larger pyramid caps. Independent Grok 4.6 review of this exact candidate is GREEN, P0/P1/P2 = 0.

Grading metrics, thresholds, tolerances, verifier, harness, tapes and population are unchanged. Other money-admission and whole-order-drop rules keep their existing scope.

Candidate snapshot: 32ca651ff1401aa23bb8caeaf96948e3a90448424cae25e3f15a849e52a3c355 (788,853 bytes).