fix(ta): align PercentRank float comparisons

[luisleo526]

Summary

• apply Pine fixed-band float equality inside ta.percentrank internal less-than-or-equal comparisons
• preserve exact equality for infinities, reject na, and retain normal ordering outside the finite abs(left-right) <= 1e-10 band
• share the rule across causal compute and same-bar recompute
• pin the merged corpus artifact commit from pineforge-corpus PR fix(ta): RMA Pine reference formula + disable FP contraction #14

The target adjacent values differ by only 2.27e-13. The old raw comparison kept the rank at 6 to 6; the fixed band produces 6 to 8 and recovers the sole missing TradingView trade without losing any prior exact match.

Validation

• exact final head a1ca227: clean Release build and CTest 112/112
• focused PercentRank boundary, na, infinity, and recompute tests pass
• merged codegen suite 1,358 passed / 2 skipped; relevant comparator tests 30 passed / 2 skipped
• exact-base OFF corpus: 252/252, 246 Excellent / 5 Strong / 1 anomaly
• ON corpus: 252/252, 247 Excellent / 4 Strong / 1 anomaly
• bytewise OFF/ON diff changes exactly 1/252 tapes: ta-percentrank-mean-reversion-01
• narrowed merged-gitlink verifier and report self-test pass at 247/4/1
• forced-no-cache scraper gate: 412/412 accounted, 0 unresolved timeouts, 0 UP / 0 DOWN; board remains 346/47/4/5

No Pine source, TradingView export, feed, verifier threshold, or tier rule changed.