feat: integrate Focus SIS for KIPP Miami

[cbini]

Integrate Focus SIS (PostgreSQL) into the data platform for KIPP Miami, replacing PowerSchool as the SIS.

Scope

• Extraction: dlt sql_table → BigQuery (daily full-replace)
• dbt: New focus source-system project with staging + intermediate models
• Dagster: kippmiami code location wiring, schedule, 1Password/k8s config
• kipptaf: Regional sources to expose Focus data to the network data mart

Design spec

docs/superpowers/specs/2026-04-03-focus-sis-integration-design.md