Fix timestamps exposed to LLM to be in local timezone (#139825)

Co-authored-by: Michael Hansen <mike@rhasspy.org>

homeassistant/helpers/llm.py

@@ -687,6 +687,11 @@ def _get_exposed_entities(
         if include_state:
             info["state"] = state.state
 
+            # Convert timestamp device_class states from UTC to local time
+            if state.attributes.get("device_class") == "timestamp" and state.state:
+                if (parsed_utc := dt_util.parse_datetime(state.state)) is not None:
+                    info["state"] = dt_util.as_local(parsed_utc).isoformat()
+
         if description:
             info["description"] = description