refactor: ui/ux polish

fix: hide schema internals in model rejection

feat: double-quoted comparison literals for schema validation

fix: reject trailing SQL comparison operators

feat: add schema-aware validation

fix: reject bare negated model predicates

fix: unsupported data mutation routing

fix: enforce model SQL output boundary

feat: clarify response sources and validate model SQL output

feat: normalize SQL questions and add deterministic SQL routing

refactor: model scope for sql query only

refactor: split chat flow from SQL routing

chore: double call fix and build_generation_prompt history injection bug fix