fix(engine): align 1x long opening affordability

[luisleo526]

What changed

• model 100%-margin long opening affordability as an explicit one-shot fill event
• exempt only zero-cost, omitted-quantity, frozen 100%-equity market entries placed and filled independently from flat
• preserve commissioned entries, explicit/priced orders, reversals, paired reentries, and accepted adds
• ignore non-positive bookkeeping lots when aggregating opening fees
• add mutation-killing coverage for flat gaps, commissions, paired reentry, accepted/rejected/zero-effect adds, cash-per-order fees, reversals, RAW orders, and engine reuse

Why

The engine re-tested independently flat all-in market entries at the actual gap fill and emitted 49 same-bar phantom margin-call fragments for the cihano validation target. The fix removes those raw artifacts while retaining TradingView-confirmed entry-time margin calls in commissioned and paired-reentry strategies.

Validation

• full configured build: pass
• ctest: 83/83
• corpus: 252/252; 239 excellent / 12 strong / 1 anomaly
• full scraper sweep: 412 strategies; 32/32 shards; stable error inventory; 0 up / 0 down
• cihano raw engine trades: 265 → 216; zero-duration phantoms: 49 → 0
• five margin sentinels: excellent, countAbsDelta 0
• 33/33 graded 3commas headlines unchanged

Exact R7-reviewed diff SHA-256: 301427f5fa89afe9dbbb74bcffd44ef4dd54014fdacb21b28c250fccf.