arcgis-to-portaljs

# ArcGIS Hub → PortalJS ## Overview Migrate an entire **ArcGIS Hub** open-data site into a **PortalJS Arc** portal in one pass. Every Hub site is machine-readable — a DCAT-US catalog at `/data.json`, with every dataset backed by an ArcGIS REST FeatureService — so migration is a **harvest → export → convert → publish → verify** pipeline that runs almost fully automated on the operator's machine, no server-side compute. The tooling is the reusable `arcgis-to-portaljs` migrator: input is one Hub URL, output is a ready-to-deploy PortalJS catalog plus a parity report. The skill is an orchestrator: it reuses the DCAT-US harvest from `portaljs-migrate`, the `ogr2ogr`/`tippecanoe`/`duckdb` dual-tier conversion from `portaljs-add-geo`, and the bulk Git-LFS → R2 push from `portaljs-migrate`. Its novel parts are the FeatureService REST export loop (paged features, not just a link) and the source-vs-derived parity report. ## Prerequisites - A scaffolded PortalJS portal whose template ships `components/MapPreview.tsx` and `components/GeoQuery.tsx` (PR #1647 or later). Run `portaljs-new-portal` first if none. - Native CLIs: **GDAL** (`ogr2ogr`, `ogrinfo`), **tippecanoe**, **duckdb** (with `spatial`), and **jq**. macOS: `brew install gdal tippecanoe duckdb jq`; Debian/Ubuntu: `apt-get install gdal-bin duckdb jq` plus tippecanoe (apt or build from source); Windows via WSL. The skill hard-stops with the install hint if any is missing. - Arc credentials for the Git-LFS → R2 push (...