Add Place schema to venue page

Problem

The /venue/ page has no Place structured data. All the required data is already available in hugo.toml params (venueAddress, venueMapLat, venueMapLon, venuePhone, venueWebsite), but it is not exposed as JSON-LD.

Without a Place schema, Google cannot confirm the venue entity in its Knowledge Graph, and the page misses potential Google Maps integration.

Proposed fix

Create a venue-specific structured data partial and call it from layouts/venue/list.html:

```json
{
"@context": "https://schema.org",
"@type": "Place",
"@id": "https://2026.pycon.ie/venue/#place",
"name": "Trinity College Dublin",
"url": "https://www.tcd.ie/",
"telephone": "+353 1 896 1000",
"address": {
"@type": "PostalAddress",
"streetAddress": "College Green",
"addressLocality": "Dublin",
"postalCode": "Dublin 2",
"addressCountry": "IE"
},
"geo": {
"@type": "GeoCoordinates",
"latitude": 53.3438,
"longitude": -6.2546
}
}
```

Files to change

• Create layouts/partials/structured-data-venue.html
• Call it from layouts/venue/list.html

Start with layouts/venue/list.html and inspect the venue parameters in hugo.toml, then review the existing layout partial conventions. Create layouts/partials/structured-data-venue.html and call it from the venue template; done means the rendered /venue/ page exposes the requested Place JSON-LD using those parameters.