feat(mcp): add paginated history tools

[hubab1]

Summary

• add read-only list_keyword_ranking_history, list_keyword_ranking_results, and list_rating_history MCP tools
• keep ranking data scoped to the requested app and its currently tracked queries
• provide stable keyset pagination, date/filter validation, persisted source evidence, and bounded nested ranked-app rows
• reject malformed optional arguments and oversized filters/cursors instead of silently broadening a query

Performance and safety

• history parent pages are capped at 50 and nested responses at 500 ranked-app rows
• child rows are loaded with one bounded batch query per tool, with a 10,000-row scan ceiling
• cursor scope is represented by a fixed-size SHA-256 digest and pagination tie-breakers use explicit lexical ordering
• all tools are annotated read-only and closed-world

Validation

• 48 focused MCP service/server tests passed
• 219 full-suite tests passed
• the pagination stress test was repeated three times
• signed Debug build succeeded, launched successfully, and was terminated after verification
• independent correctness, security/performance, and test reviews completed with no remaining P1/P2 findings

Attribution

Tool names and the history-query concept were inspired by PR #8 by @akshaynexus. This implementation is an independent rewrite against current main with bounded, deterministic pagination. No commits were cherry-picked.