Data quality: DLT expectations, quarantine tables, SLA monitor

[EduardPetraeus]

• DLT Expectations on silver layer
• Quarantine tables (bronze.quarantine_)
• Data SLA monitor (gold.data_sla_status)
• dbt schema tests on all 17 silver tables
• Unity Catalog Tags (pii_level, domain, freshness_sla)
• Data strategy interview session → docs/data_strategy.md

[EduardPetraeus]

Fully complete after Session 3: quality_rules.yaml expanded to 48 tables, 6 check types (incl. schema_drift), dbt _schema.yml, bronze validation tests.