Docs: add OpenWeather to the weather widget

[SandObserver]

Summary

• Add an OpenWeather entry to the weather widget service list: API key, activation delay, and location search staying on Open-Meteo.
• Add the Service and API key settings to the weather settings list, and name both services in the page description.
• List Open-Meteo and OpenWeather for Weather in the widgets index.
• Sync widget and admin script copies with the app, including the weather manifest, data handler and locale catalogs.

Testing
npm run build and npm run check pass. No visual component or preview layout changed.

Checklist

• npm run build and npm run check both pass.
• Product UI is shown by running or capturing it, never recreated in CSS.
• Any new preview or screenshot carries no private hostnames or real data.
• Visual changes verified in both colour schemes and both docs themes.
• Links to the app repo still resolve.

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