fix: move CREATE INDEX statements after ALTER TABLE migration in memory_store schema to prevent UndefinedColumnError on startup

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

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

10x Code Quality: Fix crash bug, cache LLM singletons, optimize batch inserts, purge stale references

Initial commit for Chronos OS MVP