feat(retrieval): add and execute sealed Phase 4 evaluation

[Odenknight]

Summary

• add the sealed Phase 4 retrieval-evaluation contract pack, schemas, generators, and 24-query hermetic reviewed bundle
• execute sealed general fixtures and the optional reviewed overlay through unactivated schema-3 stores and the actual public coordinator with exact offline provider/counter replay
• add nested gkx retrieval eval|tune, deterministic presentation, private filesystem capabilities, and guarded durable no-clobber candidate-TOML publication
• preserve the Phase 0-3 public surface while keeping raw corpus/provider/tuning/filesystem/output authority host-private

Verification

• npm test — 567/567
• npm run typecheck
• npm run build
• npm run pack:check — 337 files / 1,519,344 bytes
• npm run check:license
• npm run check:nomenclature
• focused Phase 4 Slice-B replay — 23/23; exhaustive 21,600-attempt tune replay included
• frozen retrieval/evaluation/authority/CLI replay — 162/162
• reciprocal Full/Lite Slice-A and Slice-B reviews — no blocker, HIGH, or MEDIUM findings

Scope

Draft review only. This PR does not merge, tag, release, deploy, or publish a package.

September 14, 2026 disposition

Closed as already integrated. Exact PR head 98f4faf227320852006f5e1e9e01eb41f5fdff7b is an ancestor of main 91433b158b4b9bc30bd4d43b7dd8f61363647960, verified with git merge-base --is-ancestor. No additional merge or feature admission is needed. Evidence branches are retained; this closure grants no release or runtime authority.

Exact disposition ledger.