Unified question interface

The unified question interface routes structured queries to DuckDB SQL within DataLens. The unified question interface routes semantic search queries via Qdrant in DataLens. The Unified analysis page implements the unified question interface providing a combined SQL and semantic query experience. The unified ask use case is realized by the Unified /ask endpoint integrating structured and semantic querying. The unified ask capability is realized in Phase C, which provides a unified question interface combining SQL and semantic routing.