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>

apps/api/src/modules/osm-sync/infrastructure/cron/osm-sync-cron.service.ts

@@ -77,4 +77,19 @@ export class OsmSyncCronService {
       await this.osmSync.run({ layer: 'industrial-parks', chunk, wait: true });
     }
   }
+
+  /** Refresh proximity / density mat views every Sunday after the weekly
+   *  ward sync had time to settle. Always runs (cheap, no Overpass). */
+  @Cron('0 4 * * 0', { timeZone: 'Asia/Ho_Chi_Minh' })
+  async weeklyRefreshViews(): Promise<void> {
+    try {
+      await this.osmSync.refreshMaterializedViews();
+    } catch (err) {
+      this.logger.error(
+        `Refresh views failed: ${err instanceof Error ? err.message : err}`,
+        err instanceof Error ? err.stack : undefined,
+        'OsmSyncCronService',
+      );
+    }
+  }
 }