feat(climate): configure climate.worldmonitor.app hostname variant

## Summary

Configure `climate.worldmonitor.app` as a distinct hostname variant in the frontend, similar to existing `tech`, `finance`, `happy`, and `commodity` variants.

## Changes

### `src/config/variant.ts`

Add `climate` variant:
```ts
climate: {
defaultPanels: ['climate-anomalies', 'co2-monitoring', 'climate-disasters', 'ocean-ice', 'air-quality', 'climate-news'],
mapLayers: ['climate-anomalies-heatmap', 'disasters', 'air-quality', 'wildfire'],
theme: { primaryColor: '#00AA55', accentColor: '#FF6600' },
refreshIntervals: { anomalies: 3 * 60, co2: 24 * 60, disasters: 6 * 60, news: 30 },
i18n: { title: 'Climate Intelligence', subtitle: 'Atmospheric, Ocean & Disaster Monitoring' },
}
```

### Hostname Detection

Check existing subdomain detection logic (used for `tech.worldmonitor.app`, `finance.worldmonitor.app`, etc.) and add `climate` to the recognized variants.

### Vercel

Add `climate.worldmonitor.app` to the project's domain list in Vercel dashboard.

## Depends on
#2474

Start in src/config/variant.ts and inspect the existing hostname detection used for the tech, finance, happy, and commodity variants. Add the climate configuration, register climate in hostname detection, and add climate.worldmonitor.app to the Vercel domain list; done means the hostname loads the climate panels, layers, theme, intervals, and titles.

Written by the indexing model from the issue text.