Show Open-Meteo air quality in the weather panel

[loraque-git]

Why

The weather popup already uses Open-Meteo for the daily forecast. It does not show air quality. Several community weather plugins add an AQI cell; stock omarchy.weather still has none.

What

When Open-Meteo's air-quality API returns a reading, the current-conditions row grows an AIR cell next to humid (US AQI with imperial units, European AQI with metric). Unhealthy-and-worse uses the urgent color. If the fetch fails or there is no index, the cell stays hidden — same as a missing forecast.

Coordinates are the same stored or wttr nearest_area pair the daily forecast already uses (openMeteoCoordinates in Model.js). Retry matches the daily forecast: three attempts, 2.5s apart.

No extra bar icon, no new settings form. The cell is display-only.

Tests

bash test/shell.d/weather-test.sh — existing weather assertions plus:

• stored vs wttr coordinates for Open-Meteo
• US / European AQI bands
• parse / invalid JSON
• panel fetches air-quality-api.open-meteo.com and labels the cell AIR

Test plan

• Open the weather popup with a pinned location: AIR cell appears with a category and number
• Toggle metric/imperial: scale follows (European vs US)
• Auto-detect (no pinned coordinates): AIR appears after wttr reports an area
• Offline / failed air-quality fetch: FEELS / WIND / HUMID unchanged, no empty AIR cell