- AlertNotifier / HealthAlertNotifier: richer email templates, robust
  dispatch, header-injection hardening
- Redactor + MetricsCollector + RecordWriter: additional scrubbing and
  drain improvements
- SqliteBuffer / ConnectionHandler / DrainWorker: minor robustness fixes
- MultiIngest: surface errors instead of swallowing
- New migration: add environment column
- New tests: EmailTemplate, HealthAlertNotifier, HealthReporter, HealthServer

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>