poi-index: Grafana dashboard/alert, docs, privacy manifest

- planner dashboard: replace Overpass panels with POI index freshness +
  serving panels (age, rows/category, import status, API request rate/errors)
- alerts: replace overpass-upstream-unhealthy with poi-index-stale (>6 weeks)
- architecture.md: POI data flow now the self-hosted index
- privacy manifest (DE+EN): Overpass is Journal-surface-backfill-only;
  Planner POIs served same-origin from /api/pois
- self-host-overpass README + roadmap: superseded for POIs by poi-index
- poi-extract README: self-hoster story (optional pipeline, regional extract,
  graceful empty index)
- map-core tsconfig: exclude *.sync.test.ts from tsc to keep it zero-dep

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

docs/ideas/self-host-overpass/README.md

@@ -1,4 +1,4 @@
-# self-host-overpass (parked)
+# self-host-overpass (parked — superseded for POIs)
 
 Full OpenSpec artifact set (`proposal.md`, `design.md`, `specs/`, `tasks.md`)
 for hosting our own Overpass API. Moved here from `openspec/changes/` so it
@@ -7,11 +7,22 @@ under `openspec/changes/` when ready to implement.
 
 ## Status
 
-**Parked.** The interim proxy work (`/api/overpass` → `overpass.private.coffee`,
-see `apps/planner/app/routes/api.overpass.ts`) covers the day-one needs:
-User-Agent compliance, same-origin check, rate limiting, server-side cache
-with coalescing, bbox quantization, Grafana observability. That buys us time
-before we need to own the upstream.
+**Superseded for the Planner's POI overlays** by the
+[`poi-index`](../../../openspec/changes/poi-index/) change (shipped), which
+removes Overpass from the POI path entirely: instead of running the Overpass
+software, a monthly osmium extract feeds a self-hosted PostGIS `planner.pois`
+index served at `/api/pois`. That is lighter than this plan (no Overpass
+engine, no diff replication, no RAM ceiling) and covers every current POI need
+— all queries were simple tag-in-bbox lookups that never used Overpass QL.
+
+The former interim proxy (`/api/overpass` → `overpass.private.coffee`) has been
+**removed**.
+
+**Still relevant if** we ever need genuine Overpass QL (arbitrary ad-hoc
+queries, recursion, `around:`, set operations) that a precomputed category
+index can't answer — that's the remaining reason to revive this. The Journal's
+surface-breakdown backfill still queries public Overpass instances for way
+geometry; owning that upstream is the other revive trigger.
 
 ## When to revive