[HmnDev-Tech]

Summary

Adds two new cards to the main weather screen plus a settings section to configure them. No build or CI changes — purely feature code.

AI advice card (What to wear today)

• A new card on the main screen sends a compact summary of the current weather (temperature, feels like, humidity, wind, rain chance, high/low, active alerts) to an LLM and renders short advice: what to wear, whether to take an umbrella, best time to go outside, one health tip.
• Default model: gemini-3.5-flash-lite via the Google AI Studio API (generativelanguage.googleapis.com), chosen for low latency and low cost at small request volumes.
• The API key is entered in Settings → AI advice and stored on-device only (same pattern as weather provider keys); the key is sent only to the selected provider.
• Provider selection between cloud providers:
  • Gemini (AI Studio) — native generateContent endpoint, free-key link in settings.
  • OpenAI — OpenAI-compatible /chat/completions, custom model + base URL.
  • OpenRouter — OpenAI-compatible, custom model + base URL.
• Model name and base URL are editable per provider with sensible pre-filled defaults.
• All card states handled: no key yet (button straight to settings), loading, error with the message shown, cached advice with a refresh button.

Air quality (AQI) card

• A standalone card fetching live data from the Open-Meteo Air Quality API (no API key required): US AQI, PM2.5, PM10, O3, NO2.
• Category label with color coding: Good / Moderate / Unhealthy for sensitive groups / Unhealthy / Very unhealthy / Hazardous.
• Uses the same location resolution as the weather data (manual location first, then device location).
• Manual refresh button; the data source is credited in the card footer.

Both cards are added to the portrait layout and the wide/two-pane (tablet/foldable) layout.

Files changed

• weather/ai/AiProviders.kt, weather/ai/AiAdvisor.kt — provider registry and Gemini / OpenAI-compatible client (HTTP via the existing ProviderHttp).
• weather/aqi/AqiRepository.kt — Open-Meteo air quality fetch + category mapping.
• ui/features/weather/AiAdviceCard.kt, ui/features/weather/AqiCard.kt — the two new cards.
• ui/features/weather/AiSettingsUI.kt — new settings section, mounted in SettingsActivity.
• ui/features/weather/WeatherDetailSheet.kt — cards inserted in both layouts.
• data/repository/SettingsRepository.kt — AI provider / model / base URL / key storage (SharedPreferences, same pattern as weather keys).
• res/values/strings.xml — new strings.

Testing

• Local: ./gradlew assembleGithubDebug succeeds on JDK 21 / Android SDK 37.1; all new Kotlin code compiles.
• Not run: assembleGithubRelease (minified build).
• Manual on-device testing of the AI/AQI cards not performed yet — feedback welcome.

Notes for maintainers

• Privacy: the API key and weather summary are only sent to the provider the user selected; nothing else leaves the device and nothing is logged.
• Strings are English-only, matching the current values/strings.xml; happy to add translations if there is a localization flow.
• The AI settings section renders below the existing settings groups and the cards render below the details card, so existing sections are untouched.