I am not quite sure why this is so complex. I use GMT (Greenwich Mean Time) or what is now called UTC Universal Coordinated Time for log file entries and database entries. I convert that time into local time for user presentation when needed. There are a number of modules that do this very well.

There is no ambiguity with a UTC time. When you set your local clock back or forward one hour, the UTC time marches onward - it is a continuously incrementing number - UTC has no concept of "daylight savings time". I avoid having chron jobs start between 1:00-2:00 am local time as this is a boundary condition when the local time might "revert" to a previous time.