feat(osm): Phase 6 — proximity materialized views + refresh cron

* `mv_park_nearest_poi` — for each IndustrialPark, the 3 nearest POI of
  six priority categories (HOSPITAL/BANK/GAS/BUS/METRO/POLICE) within
  5km. Refreshed weekly. Pre-aggregated 6,513 rows from the live
  catalog so the KCN sidebar can render in <50ms instead of running
  ST_Distance for every page hit.
* `mv_poi_density_by_province` — count of POI per (province, category)
  for analytics heatmaps.
* `OsmSyncService.refreshMaterializedViews()` calls
  `REFRESH MATERIALIZED VIEW CONCURRENTLY` so reads aren't blocked.
* New cron entry `weeklyRefreshViews` (Sun 04:00 ICT) and admin
  endpoint `POST /admin/osm/refresh-views` for on-demand refresh.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

prisma/migrations/20260501030000_add_poi_proximity_views/migration.sql

@@ -0,0 +1,39 @@
+-- Phase 6: cached proximity scores for fast filter / sort.
+-- Refreshed by `OsmRefreshViewsCron` (Sun 03:00 ICT) and on admin-trigger.
+
+-- For each industrial park, the 3 nearest POI of each priority category.
+CREATE MATERIALIZED VIEW IF NOT EXISTS "mv_park_nearest_poi" AS
+SELECT
+  p.id AS park_id,
+  poi.category::text AS category,
+  poi.id AS poi_id,
+  poi.name AS poi_name,
+  ROUND(ST_Distance(p.location::geography, poi.location::geography)::numeric, 0)::int AS distance_m,
+  ROW_NUMBER() OVER (
+    PARTITION BY p.id, poi.category
+    ORDER BY ST_Distance(p.location::geography, poi.location::geography)
+  ) AS rank
+FROM "IndustrialPark" p
+CROSS JOIN LATERAL (
+  SELECT id, name, category, location
+    FROM "Poi"
+   WHERE "isPublic" = true
+     AND category::text IN ('HOSPITAL','BANK','GAS_STATION','BUS_STATION','METRO_STATION','POLICE')
+     AND ST_DWithin(location::geography, p.location::geography, 5000)
+) poi;
+
+CREATE INDEX IF NOT EXISTS "mv_park_nearest_poi_park_cat" ON "mv_park_nearest_poi"(park_id, category, rank);
+CREATE UNIQUE INDEX IF NOT EXISTS "mv_park_nearest_poi_uq" ON "mv_park_nearest_poi"(park_id, category, poi_id);
+
+-- Per-province POI density (count by category) for analytics heatmaps.
+CREATE MATERIALIZED VIEW IF NOT EXISTS "mv_poi_density_by_province" AS
+SELECT
+  "provinceCode",
+  category::text AS category,
+  COUNT(*)::int AS poi_count
+FROM "Poi"
+WHERE "isPublic" = true
+  AND "provinceCode" IS NOT NULL
+GROUP BY "provinceCode", category;
+
+CREATE INDEX IF NOT EXISTS "mv_poi_density_by_province_idx" ON "mv_poi_density_by_province"("provinceCode", category);