fix(industrial): improve OSM review UX + public map visibility

Four UX issues surfaced when reviewing the new OSM-sync pipeline against
the actual 2,193 imports — fixed in this commit:

1. Admin queue surfaced noise first.
   `ListOsmPendingHandler` now sorts by `totalAreaHa DESC` (real KCN
   first, single-factory `landuse=industrial` polygons last) and accepts
   `minAreaHa` (default 50 ha) plus a `region` filter. The admin page
   exposes both as dropdowns — "Tất cả / ≥ 5 / ≥ 50 / ≥ 200 / ≥ 500 ha".
   Top-of-queue is now Bàu Bàng (2,597 ha) and Nhơn Trạch (2,535 ha).

2. Promote dialog said "KCN KCN Đại An" — duplicate prefix.
   Reworded to "Sắp promote: <name>" so the row name stands on its own.

3. Province was "Chưa xác định" on 2,107 of 2,193 OSM rows.
   The OSM tags lacked any addr:* hint, so the importer never had
   anything to write. Added `scripts/data/vn-province-centroids.ts` (63
   provinces with capital-city coords) and a `nearestProvince(lat, lng)`
   fallback in `parseFeature()`. Shipped a one-shot backfill script
   `scripts/backfill-osm-provinces.ts` and ran it — every existing OSM
   row now has a province (Hồ Chí Minh: 408, Lạng Sơn: 232,
   Quảng Ninh: 220, Hà Nội: 172, Hải Phòng: 105, …). Admin can correct
   on promote if the nearest-centroid heuristic picked the wrong
   neighbour for a long-thin province.

4. Public map looked empty — only 20 curated parks visible.
   Added an opt-in toggle "Hiển thị KCN OSM" with a small legend above
   the map. When on, the bbox endpoint returns OSM raw rows too; markers
   render in amber (vs. green for curated) at slightly smaller radius
   and lower opacity, so the visual hierarchy stays clear. Refetch is
   wired through a ref so the toggle takes effect without remounting
   the map.

Verified in browser preview: zoom-out shows clusters of 320 / 71 / etc.
across the country with the toggle on, and just three small clusters
(20 curated parks) when off.

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

scripts/sync-osm-industrial-parks.ts

@@ -25,13 +25,14 @@
  */
 import 'dotenv/config';
 import { createId } from '@paralleldrive/cuid2';
-import area from '@turf/area';
-import centroid from '@turf/centroid';
 import { PrismaPg } from '@prisma/adapter-pg';
 import { type Prisma, PrismaClient } from '@prisma/client';
+import area from '@turf/area';
+import centroid from '@turf/centroid';
 import type { Feature, MultiPolygon, Polygon, Point } from 'geojson';
 import osmtogeojson from 'osmtogeojson';
 import pg from 'pg';
+import { nearestProvince } from './data/vn-province-centroids';
 
 const generateCuid = (): Promise<string> => Promise.resolve(createId());
 
@@ -200,10 +201,14 @@ function parseFeature(
     totalAreaHa = Math.round((area(feat as Feature) / 10000) * 100) / 100;
   }
 
+  // Province resolution: prefer explicit OSM tags, then fall back to a
+  // nearest-centroid lookup against our 63-province table. The fallback
+  // catches the (very common) case where Vietnamese landuse polygons have
+  // no addr:* tags at all.
   const province =
     VN_PROVINCE_HINTS.map((k) => tags[k]).find(Boolean) ??
     tags['addr:city'] ??
-    'Chưa xác định';
+    nearestProvince(cLat, cLng);
   const district = tags['addr:district'] ?? tags['addr:suburb'] ?? '';
   const address =
     tags['addr:full'] ??