feat: Add AVWX as international TAF/METAR source

[Orinks]

Summary

Add AVWX REST API as an aviation weather data source to provide international TAF/METAR support. Currently AccessiWeather decodes TAFs from NOAA, which covers US stations. AVWX would extend aviation weather to any ICAO station worldwide.

Why AVWX?

Global Coverage

• Pulls from NOAA ADDS (worldwide) plus additional regional sources
• Any ICAO station globally: EGLL (London), RJTT (Tokyo), YSSY (Sydney), LFPG (Paris), etc.
• Station lookup by ICAO code, lat/lon, or nearest search

Accessibility-First Features

• Built-in TTS strings — spoken-ready summaries per element and full report, designed for text-to-speech. Huge win for screen reader users.
• Plain English translation — converts raw TAF elements into readable English (e.g. "Broken clouds at 2000ft, rain" instead of "BKN020 RA")
• Flight rules calculation — VFR/MVFR/IFR/LIFR computed per time period
• Error correction — sanitizes common manual entry mistakes in TAFs

Additional Data Beyond TAFs

• METAR (current conditions at airports)
• PIREP (pilot reports of inflight conditions)
• AIRMET/SIGMET (inflight weather advisories: turbulence, icing, thunderstorms)
• NOTAM (notices affecting airport/flight operations)
• NBM (NOAA National Blend of Models forecasts up to 8 days)
• Station info (name, identifiers, coordinates, runways)

API Details

• Free tier: Basic METAR and TAF parsing, no credit card required
• Open-source project tier: Higher call limits for OSS maintainers
• Auth: API key (free registration)
• Format: JSON, XML, or YAML
• Docs: https://avwx.docs.apiary.io
• GitHub: https://github.com/avwx-rest
• Open source — all code available for security audit

Implementation Notes

• Use AVWX for international ICAO stations, keep existing NOAA source for US stations
• Leverage AVWX translation and TTS features for accessible TAF presentation
• Flight rules (VFR/MVFR/IFR/LIFR) per period could be surfaced in the UI
• Consider adding PIREP and SIGMET data as optional aviation weather layers
• Station search by coordinates could auto-detect nearest airport for the user's location

References

• API docs: https://avwx.docs.apiary.io
• Info: https://info.avwx.rest/
• Pricing: https://account.avwx.rest
• Support: https://support.avwx.rest
• GitHub: https://github.com/avwx-rest