Add blog post for TemperatureConverter.convert_interval deprecation (#2854)

Author: krahabb

blog/2025-11-04-convert-interval-deprecation.md

@@ -0,0 +1,10 @@
+---
+author: Davide Perteghella
+authorURL: https://github.com/krahabb
+title: "TemperatureConverter.convert_interval deprecation"
+---
+
+The method `convert_interval` in `TemperatureConverter` (allowing conversions between °F and °C intervals) has been deprecated in favor of `TemperatureDeltaConverter.convert`.
+The new converter and device class are now the preferred way to deal with temperature intervals.
+
+For details, see [core PR 155689](https://github.com/home-assistant/core/pull/155689) and [core PR 147358](https://github.com/home-assistant/core/pull/147358).