fix: preserve residual long after repeated percent sell entry

[luisleo526]

Repeating a default-percent short entry with the same ID in one bar could close the entire existing long and open a new short. For the confirmed ordinary next-open case, the engine now executes the frozen sell quantity, preserves any long remainder and its bracket lifecycle, and cancels later sell siblings. Exact replacement provenance and risk-direction guards preserve the other order paths.

Validated on engine c022c40ebca11fd73a087b563c30fb813046fbe8 with codegen 3fd97fe28abd7b191cb376d9f5db4e056fcfae4b:

• Cloud Run measured all 4,190 probes in 72/72 cases. Jevon XAUUSD moves from strong to excellent, count difference 2 to 0; all 260 target entry/exit rows match TradingView on side, time, price and quantity. The other 4,189 canonical results are unchanged, with zero regressions, errors, gaps or new moderate results.
• Gate pineforge-pr-gate-hvgzv: PASS, target score +1, and zero regressions or tolerated exceptions across 704 hard probes. Result: 4,159 excellent / 30 strong / 1 moderate.
• Fresh build and 212/212 tests passed, including 95 focused checks. Eleven covered TradingView controls establish the behavior and its directional boundary. Independent Grok 4.6 review of this exact candidate is GREEN, P0/P1/P2 = 0; all prior review findings are resolved.

Grading metrics, thresholds, tolerances, verifier, harness, tapes and population are unchanged. The buy-side replacement behavior remains outside this repair.

Candidate snapshot: 0b80b0726dea11aa41fb4b1adf828c527f6a2694f8733aff1c0c3fff0bf017e9 (788,862 bytes).