Fix IIIF Leaflet CRS bounds

[ewlarson]

Summary

• Replace the plugin-dependent IIIF Image API path with a local Leaflet tile layer modeled after the abcdefgeo implementation.
• Fetch info.json, compute native zoom, build L.CRS.Simple image bounds from pixel dimensions, and constrain panning with padded max bounds.
• Avoid the basemap/geosearch path for IIIF image viewers so image maps do not trigger stray basemap tile requests.
• Explicitly import the Leaflet fullscreen plugin and keep fullscreen/opacity controls available for IIIF images.
• Add focused coverage for CRS.Simple bounds, tile URL generation, clipped edge tiles, and blank out-of-image tiles.

Why

IIIF Image API resources need Leaflet's simple image coordinate space, not geospatial basemap coordinates. The previous fix selected CRS.Simple, but it still relied on the leaflet-iiif plugin lifecycle and did not compute image bounds from info.json before fitting/constraining the map. That left rough pan/zoom behavior and impossible tile requests.

Impact

Image-service-only IIIF resources render as bounded image maps with predictable zoom and pan behavior. IIIF Presentation manifests continue to use Mirador, and normal geospatial Leaflet resources continue through the GeoBlacklight path.

Validation

• npm test -- run src/__tests__/geoblacklight/leaflet_viewer_controller.test.js src/__tests__/components/resource/ResourceViewer.test.tsx
• npm run build