Fix minute_data function to use days parameter instead of self.forecast_days

The minute_data function has a 'days' parameter but was incorrectly using
self.forecast_days in one location (line 655) when calculating to_time.
This could cause inconsistent behavior when the function is called with
a different days value than self.forecast_days.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: mgazza

apps/predbat/fetch.py

@@ -652,7 +652,7 @@ def minute_data(
             if to_key:
                 to_value = item[to_key]
                 if not to_value:
-                    to_time = now + timedelta(minutes=24 * 60 * self.forecast_days)
+                    to_time = now + timedelta(minutes=24 * 60 * days)
                 else:
                     to_time = str2time(item[to_key])
             else: