feat: add user webhooks, SSE fallback, alert ack/snooze, and email delivery channel - #379

…livery channel (Neurowealth#368, Neurowealth#369, Neurowealth#366, Neurowealth#367)

- Add user-scoped outbound webhooks with per-user HMAC secrets, SSRF guards, and server-side event filters (Neurowealth#368)
- Add Server-Sent Events (SSE) fallback transport, single-use stream tickets, and resumable Last-Event-ID replay (Neurowealth#369)
- Add AlertFire / AlertAck models, snooze workflow, ackToken signing, and un-acknowledged escalation counting (Neurowealth#366)
- Add provider-abstracted Mailer (SES/SMTP), verified opt-in flow, and bounce/complaint webhook processing (Neurowealth#367)
- Add documentation (USER_WEBHOOKS.md, REALTIME_STREAMING.md, ALERTS.md, NOTIFICATIONS.md) and Jest unit test suite

Closes Neurowealth#368, Neurowealth#369, Neurowealth#366, Neurowealth#367

…Neurowealth#368, Neurowealth#369, Neurowealth#366, Neurowealth#367)

- Relocate test suites from src/ to tests/unit/ matching Jest roots config
- Remove invalid vitest imports and rely on Jest test runner globals
- Add explicit const type assertions for FilterCondition operators
- Apply Prettier formatting across all updated src and test files
- Fix npm run build and npm run format:check CI pipeline steps

…Endpoint and EmailIdentity (Neurowealth#368, Neurowealth#367)

- Rebase branch onto latest upstream/main (including PR Neurowealth#378 schema updates)
- Align relation fields on model User for userWebhookEndpoints and emailIdentity
- Verify npx prisma validate and npx prisma generate succeed cleanly

… models (Neurowealth#368, Neurowealth#367)

…file override