Per-source quality scoring implemented

Per-contact quality flags (bounce, invalid email) are only useful if you can trace them back to the source that produced them. Without per-source quality scoring you have no way to quarantine a bad purchased list, deprioritize a scraper hitting stale pages, or negotiate data credits with a vendor whose records are 40% invalid. ISO 25010:2011 §4.2.7 (data quality) requires that data accuracy be measurable and traceable. Absence of source-level aggregation means data rot goes undetected until deliverability collapses.

Add a data_sources table with a quality_score column, then populate it via a periodic aggregation query that computes bounce and invalid-email rates per source.

CREATE TABLE data_sources (
  id            TEXT PRIMARY KEY,
  source_type   TEXT NOT NULL,
  display_name  TEXT,
  quality_score NUMERIC(5,2),   -- 0–100
  last_scored_at TIMESTAMPTZ
);

-- Periodic update (run hourly or daily)
UPDATE data_sources ds
SET quality_score = (
  SELECT 100.0 * COUNT(*) FILTER (WHERE c.email_valid AND NOT c.bounced)
         / NULLIF(COUNT(*), 0)
  FROM contacts c
  WHERE c.source_id = ds.id
    AND c.acquired_at > NOW() - INTERVAL '30 days'
),
last_scored_at = NOW();