Support additional weather alerts (UV, pollen, air quality, wind, etc.)

[PhillyUrbs]

Summary

Today the dashboard shows a single rain banner. Extend the alert system to surface other actionable weather conditions for kids.

Proposed alerts

• UV index — sunscreen/hat reminder when UV >= moderate (e.g. 6+)
• Pollen — high tree/grass/weed pollen for kids with allergies (per-child opt-in)
• Air quality (AQI) — limit outdoor play when unhealthy for sensitive groups
• Wind / wind chill — high wind advisory or dangerously cold wind chill
• Heat index — extreme heat warning (hydration / shade)
• Thunderstorm — incoming storm in the next 1-2 hours
• Snow / ice — boots-and-mittens reminder; school-bus-stop ice warning

UX

• Stack multiple banners (or rotate) above the dashboard
• Each alert: short kid-friendly message + icon
• Per-alert enable/disable in Settings (some families don't care about pollen, etc.)
• Per-child overrides where it makes sense (pollen sensitivity)
• Theme-aware coloring (already wired --ui-accent for non-native frameworks; native theme keeps warm warning colors)

Data sources (free, no API key)

• Open-Meteo Air Quality API: UV, PM2.5/PM10, pollen (tree/grass/birch/alder/mugwort/ragweed/olive)
• Open-Meteo Forecast: wind speed/gusts, apparent temperature, precipitation type
• Severe weather (NWS for US) via api.weather.gov alerts endpoint

Implementation notes

• Add an alerts module that polls Open-Meteo Air Quality alongside the weather fetch
• Config schema additions: alerts.uv.enabled, alerts.uv.threshold, alerts.pollen.enabled, etc.
• Telemetry: breadcrumb on each alert raised; capture_message on alert-fetch failure
• Tests: fixtures for high-UV, high-pollen, AQI-unhealthy, thunderstorm scenarios

Out of scope (for this issue)

• Push notifications / sound alerts
• Hourly alert timeline visualization (separate issue)