[P14] A-6 — Merge Phase 14 Branch to `develop` + Version Bump to v0.5.8

[coeusyk]

Background

Phase 14 (phase/14-eval-optimization) closes once all Elo-positive changes have cleared SPRT and been accumulated on the branch. This issue is the merge gate.

Pre-Merge Checklist

SPRT verdicts — must be recorded and acted on:

• A-1 king-safety verdict recorded (H1 applied or H0 documented)
• A-2 mobility verdict recorded (H1 applied or H0 documented)
• A-3 pawn-structure verdict recorded (H1 applied, H0 documented, or formal deferral written)
• A-4 aspiration window verdict recorded (winning delta applied or 50 cp retained)
• A-5 contempt verdict recorded (H1 applied or H0 documented)

Quality gates:

• engine-core test suite: 0 failures, ≤2 skips
• engine-tuner test suite: 0 failures, ≤1 skip
• NPS bench: aggregate NPS ≥ 228,490 (5% floor below Phase 13 measured 240,516)
• Net Elo gain vs v0.5.7 baseline: at least one SPRT H1 was accepted (phase closes with a real improvement, not a wash)

Documentation:

• dev-entries/phase-14.md complete: all issue verdicts, tuning runs, SPRT tables, and final recommended pipeline documented
• CHANGELOG.md Phase 14 entry complete

Work Required

• Run a full test
• Use release.yml to create a new release

Acceptance Criteria

• develop branch has clean CI (all tests green)
• Version is 0.5.8-SNAPSHOT in all pom.xml files
• v0.5.7 tag pushed
• dev-entries/phase-14.md committed
• CHANGELOG.md Phase 14 entry complete
• At least one SPRT H1 accepted across A-1 through A-5