fix: pre-release audit round 12 — 33 bugs fixed across all tiers

fix: curated model lists, reasoning model token scaling, skip temp files

fix: Round 8 audit — 15 bugs fixed across 10 files (1 CRITICAL, 7 HIGH, 3 MEDIUM, 4 LOW)

fix: 10 bugs (4 HIGH + 6 MEDIUM) from comprehensive codebase audit

fix: harden route parsing, column dedup, and column name access

fix: 7 bugs from multi-agent debug review of SQL layer

fix: 4 bugs found during comprehensive code review

feat: add LLM-powered column descriptions with codebook detection

fix: harden SQL ingest connection handling and brace-escape all prompt parameters

feat: add SQL ingestion — load tabular files into SQLite with schema registry

feat: add SQL ingestion helpers — table naming, type inference, samples