SMHI: migrate to SNOW1gv1 API (replace deprecated PMP3gv2)

[cgillinger]

Summary

This PR migrates the SMHI weather provider from the deprecated PMP3gv2 API to the new SNOW1gv1 API.

The old API (pmp3g/version/2) started returning HTTP 404 on 2026-03-31.

Changes

• Updated API endpoint:
  • pmp3g/version/2 → snow1g/version/1
• Updated response parsing:
  • validTime → time
  • parameters[] → data (flat structure)
• Updated parameter names:
  • t → air_temperature
  • ws → wind_speed
  • etc.
• Updated precipitation handling to match new predominant_precipitation_type_at_surface
• Updated coordinate parsing (flat [lon, lat])
• Added missing value handling (9999 → null)

Notes

• Maintains backward compatibility for precipitationValue config
• No UI changes
• Symbol mapping unchanged (same codes 1–27)

Testing

• Verified against live SMHI SNOW1gv1 API responses
• Confirmed old API returns HTTP 404

Impact

Fixes broken SMHI provider due to API deprecation.

[rejas]

Thanks for the PR. Did you make sure to start your work from the latest develop branch?

[cgillinger]

Thanks for the PR. Did you make sure to start your work from the latest develop branch?

I’m not entirely sure, I’ll double-check and update my branch if needed. I’m still getting familiar with the GitHub workflow.

[khassel]

I'm not a fan of these code style tests, but others here value them. Could you please remove the warnings in smhi.js? They're visible in the "files changed" tab. Thanks!