poi-index: extract pipeline (BRouter host) + import job (flagship) + e2e

- poi-extract.sh: PBF download -> osmium tags-filter -> centroid NDJSON +
  manifest, published via the Caddy sidecar at vSwitch-only /poi/*
- osmium-filters.txt + poi-selectors.sql generated from map-core selectors,
  guarded by sync tests so poiCategories stays the single source of truth
- poi-import.sh: checksum verify -> classify into category rows ->
  70% guard (--bootstrap override) -> atomic rename swap; node_exporter
  textfile metric for import outcome
- systemd service+timer units for both halves (monthly, offset)
- cd-infra.yml: ship infrastructure/scripts to the flagship
- e2e: mock /api/pois instead of /api/overpass

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

e2e/fixtures/test.ts

@@ -8,10 +8,11 @@ import { test as base, expect } from "@playwright/test";
  *
  * The trigger for this safety net was #282 — a POI test that silently
  * relied on live Overpass data for months because its `page.route`
- * was pointing at a URL the browser no longer hit after `/api/overpass`
- * was introduced. With this fixture in place, a request to
- * `overpass.private.coffee` (or any other unlisted host) would abort
- * and the test would surface the missing mock immediately.
+ * was pointing at a URL the browser no longer hit after the POI proxy
+ * was introduced. With this fixture in place, a request to any unlisted
+ * host would abort and the test would surface the missing mock
+ * immediately. (POIs are now served from the same-origin `/api/pois`
+ * index endpoint, so the map makes no third-party POI requests at all.)
  */
 const EXTERNAL_ALLOWLIST: RegExp[] = [
   // App origins served by Playwright's webServer