poi-index: map-core selectors, planner.pois schema, /api/pois route + client, metrics

Replace the planner's Overpass proxy with a self-hosted POI index:
- map-core POI categories become structured tag selectors (single source of
  truth) + osmium filter / classification helpers
- planner.pois PostGIS table (centroid points, GiST + category indexes)
- /api/pois serving route (session + same-origin + rate limit, 100 cap)
- lib/pois.ts client (renamed from overpass.ts; GET, quantized bbox)
- metrics: poi_api_requests_total + DB-collected index rows/age gauges;
  drop overpass_* metrics
- remove /api/overpass proxy + dead OVERPASS_URLS on the planner service
  (Journal surface backfill still uses it via code default)

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

infrastructure/.env.example

@@ -11,9 +11,11 @@ SESSION_SECRET=change-me
 S3_ACCESS_KEY=
 S3_SECRET_KEY=
 
-# Overpass upstream failover. Comma-separated list tried in order;
-# first 2xx response wins. Falls back to the single-URL OVERPASS_URL
-# if this is unset, and to a built-in default list if neither is set.
+# Overpass upstream failover for the Journal's surface-breakdown backfill
+# (route-surface-breakdown). Comma-separated list tried in order; first 2xx
+# response wins. Falls back to the single-URL OVERPASS_URL if unset, and to a
+# built-in default list if neither is set. The Planner no longer uses Overpass
+# — its POI overlays are served from the self-hosted `planner.pois` index.
 # OVERPASS_URLS=https://lz4.overpass-api.de/api/interpreter,https://overpass-api.de/api/interpreter
 
 # Demo-activity-bot. Only enable in prod. When true, the journal worker

infrastructure/docker-compose.staging.yml

@@ -94,7 +94,6 @@ services:
     environment:
       BROUTER_URL: ${BROUTER_URL:?BROUTER_URL must be set}
       BROUTER_AUTH_TOKEN: ${BROUTER_AUTH_TOKEN:?BROUTER_AUTH_TOKEN must be set}
-      OVERPASS_URLS: ${OVERPASS_URLS:-https://lz4.overpass-api.de/api/interpreter,https://overpass-api.de/api/interpreter}
       DATABASE_URL: postgres://trails:${POSTGRES_PASSWORD:?POSTGRES_PASSWORD must be set in SOPS secrets.app.env}@postgres:5432/${STAGING_DATABASE}
       NODE_ENV: production
       PORT: 3001

infrastructure/docker-compose.yml

@@ -103,12 +103,6 @@ services:
       # BRouter request. The Caddy sidecar on the dedicated host
       # enforces this header. Set in SOPS secrets.app.env.
       BROUTER_AUTH_TOKEN: ${BROUTER_AUTH_TOKEN:?BROUTER_AUTH_TOKEN must be set in SOPS secrets.app.env}
-      # Ordered failover list for the Overpass proxy. The code defaults
-      # to the same pair if unset; declaring it here makes the prod
-      # upstream explicit and easy to reshuffle via env when a
-      # community instance misbehaves. Override per-env with
-      # OVERPASS_URLS in the SOPS file.
-      OVERPASS_URLS: ${OVERPASS_URLS:-https://lz4.overpass-api.de/api/interpreter,https://overpass-api.de/api/interpreter}
       DATABASE_URL: postgres://trails:${POSTGRES_PASSWORD:?POSTGRES_PASSWORD must be set in SOPS secrets.app.env}@postgres:5432/trails
       NODE_ENV: production
       PORT: 3001