feat(02-01): add schema extension and core search/detail domain types
- ClickHouse schema migration SQL with 12 new columns and skip indexes
- SearchRequest, SearchResult, ExecutionSummary records in core search package
- SearchEngine interface for swappable search backend (ClickHouse/OpenSearch)
- SearchService orchestration layer
- ProcessorNode, ExecutionDetail, RawExecutionRow, DetailService in core detail package
- DetailService reconstructs nested processor tree from flat parallel arrays
- ExecutionRepository extended with findRawById query method
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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