Display OpenIndexMap v1 links and thumbnails

[ewlarson]

After merge

Summary

• normalize OpenIndexMaps v1 properties such as thumbUrl, download, and recId while retaining legacy-property support
• display item links, digital and physical holdings, identifiers, notes, and direct thumbnails for selected map sheets
• fall back to IIIF manifest thumbnails when thumbUrl is absent
• escape remote text, reject unsafe URL schemes, and announce selection updates accessibly
• publish the Docker frontend on configurable host port 5173 so it does not conflict with Rails on port 3000, with corresponding local-development documentation

Root cause

The bundled GeoBlacklight frontend renderer expects legacy OpenIndexMap property names including thumbnailUrl, downloadUrl, and recordIdentifier. Current records follow the OpenIndexMaps v1 schema, which uses thumbUrl, download, and recId; some records also expose their usable item link through digHold. As a result, the Geoportal rendered only the title and label.

Impact

Selecting an OpenIndexMap sheet now exposes its available thumbnail and actionable links, matching the v1 schema and restoring the detail shown by the previous Geoportal.

Validation

• 81 focused Vitest tests passed across the new renderer and resource views
• frontend production build passed
• targeted ESLint passed
• Docker Compose configuration validation passed
• verified the affected OpenIndexMap pages locally through the Docker frontend

Fixes #326