feat: postgres index

[iwilltry42]

Use via env export KNOW_INDEX_DSN="postgres://knowledge:knowledge@localhost:5432/knowledge?sslmode=disable"

E.g. to have a full postgres driven setup:

1. Spin up pgvector, e.g. using the provider docker-compose file: docker compose up (in the knowledge repo root)
2. Setup to use pgvector for Vector Store: export KNOW_VECTOR_DSN="pgvector://knowledge:knowledge@localhost:5432/knowledge?sslmode=disable"
3. Setup to use the exact same postgres instance for our index: export KNOW_INDEX_DSN="postgres://knowledge:knowledge@localhost:5432/knowledge?sslmode=disable"`
4. Use knowledge normally