fix: move CREATE INDEX in vector_store after ALTER TABLE migration

refactor: centralise all magic numbers into config.py driven by env vars

feat: bi-temporal supersession, scope isolation, configurable threshold, benchmark adapter

Rebrand to Kaal — rename from Chronos OS, add Logo component with serif seal design, swap all Hexagon icons for Logo

Hotfix: change blocking model async await to a background task so Render port scanner doesn't timeout

Migrate: SQLite+ChromaDB → Neon PostgreSQL+pgvector (persistent cloud storage)

Initial commit for Chronos OS MVP