After the big weather refactor (#4032), OpenWeatherMap was effectively
hard-wired to One Call v3. One Call 2.5 is deprecated and no longer
available, so it looked like v2.5 support was effectively over — but the
classic `/weather` and `/forecast` endpoints were never actually
dropped. This restores support for those.
Fixes#4100.
## What this PR does
- handles OpenWeatherMap responses by endpoint again (`/onecall`,
`/weather`, `/forecast`)
- restores v2.5 current and forecast support (including hourly via
3-hour forecast slots)
- filters outdated hourly entries centrally while keeping the current
hour visible (if available)
## Screenshot
<img width="768" height="481" alt="bildo"
src="https://github.com/user-attachments/assets/9bce3531-3731-4fd7-b41e-e20603afa725"
/>
