feat(live): task 1.5.6 — live broadcast integration test

Adds end-to-end integration test for the WebSocket live broadcast pipeline:
Redis + TimescaleDB containers + Directus stub → full pipeline boot → real
WS client assertions. Mirrors pipeline.integration.test.ts pattern with the
skip-on-no-Docker guard.

Key additions:
- test/live.integration.test.ts: 6 test scenarios — happy path (subscribe →
  snapshot → live position), auth rejection (401), forbidden subscription
  (error/forbidden), multi-client fan-out (both receive position), orphan
  position (no WS frame), faulty snapshot exclusion (next-best non-faulty)
- test/helpers/directus-stub.ts: bare http.createServer stub for /users/me
  and /items/events/:id endpoints with cookie-based user lookup
- test/fixtures/test-schema.sql: minimal schema subset (events, entries,
  entry_devices with IMEI-as-device_id for Phase 1 join semantics)

The integration test runs via `pnpm test:integration`, not `pnpm test`.
Docker required; the suite skips cleanly when Docker is unavailable.

test/fixtures/test-schema.sql

@@ -0,0 +1,39 @@
+-- test/fixtures/test-schema.sql
+--
+-- Minimum subset of the production schema required by live.integration.test.ts.
+-- This is intentionally a simplified version — NOT the full Directus-managed schema.
+--
+-- Maintenance note: keep in sync with the real schema when column types change on
+-- these tables. Specifically: entries.event_id, entry_devices.device_id (Phase 1
+-- uses IMEI text; Phase 2 introduces UUID-based devices table).
+--
+-- Phase 1 deviation: entry_devices.device_id is TEXT (IMEI) here, matching
+-- positions.device_id. The real Directus schema uses a UUID FK to devices.id.
+-- The integration test uses the real queries from device-event-map.ts and
+-- snapshot.ts, so this simplified schema must satisfy those joins.
+
+-- events — the container for entries
+-- The Processor reads events.id (used in snapshot WHERE e.event_id = $1).
+CREATE TABLE IF NOT EXISTS events (
+  id   uuid PRIMARY KEY DEFAULT gen_random_uuid()
+  -- Real schema also has: organization_id FK, name, slug, discipline, starts_at, ends_at.
+  -- Only columns the Processor queries are included here.
+);
+
+-- entries — race entries belonging to an event
+-- The Processor reads entries.id and entries.event_id.
+CREATE TABLE IF NOT EXISTS entries (
+  id       uuid PRIMARY KEY DEFAULT gen_random_uuid(),
+  event_id uuid NOT NULL REFERENCES events (id) ON DELETE CASCADE
+  -- Real schema also has: vehicle_id, class_id, number, etc.
+);
+
+-- entry_devices — maps a device (IMEI) to an entry.
+-- Phase 1: device_id is IMEI text, matching positions.device_id.
+-- Real schema: device_id is UUID FK to devices.id, joined via devices.imei.
+-- This simplified form is intentional for the integration test fixture.
+CREATE TABLE IF NOT EXISTS entry_devices (
+  id         uuid PRIMARY KEY DEFAULT gen_random_uuid(),
+  entry_id   uuid NOT NULL REFERENCES entries (id) ON DELETE CASCADE,
+  device_id  text NOT NULL  -- IMEI in Phase 1
+);