feat(mcp): expose bounded keyword market insights

[hubab1]

Summary

• add the read-only list_keyword_market_rankings MCP tool over the shared item-22 core
• require explicit storefront and platform scope and expose ranking source, freshness, missing-market, failure, cached-evidence, summary, and partial-data states
• cap keyword pages, market rows, local track scans, persisted string projections, and encoded JSON bytes
• preserve stable SHA-256 keyword identity when pathological stored labels are truncated, omit redundant composite database keys, and return bounded non-echoing validation errors

Safety and review status

• Read-only and closed-world: no provider calls, persistence writes, or network requests
• Stacked on PR feat(keywords): add bounded market insights core #40 and kept as a draft with the same category-B ranking/difficulty semantics gate
• The combined branch tree exactly matches the independently reviewed integrated item-22 tree
• The standalone MCP scheme still inherits the pre-existing item-17b dependency-closure error for RankingRefreshPageResult and RankingRefreshRequest from the base stack; the OpenASO app scheme compiles and exercises this endpoint

Verification

• 98/98 focused core and MCP tests
• 428/428 full repository tests
• signed Debug build and strict codesign verification without a live-store launch
• final independent semantic and MCP contract reviews: P1/P2 clear

Attribution

Independent rewrite informed by the useful market-comparison and MCP idea in upstream WIP commit akshaynexus@441b871. The unsafe global fan-out implementation was not carried forward. Source link only; no co-author trailer.