How can I combine two outlets into one output using OR logic?
There probably isn't anything you can buy that does this for a residential application, but it's done all the time in industrial plants, like this:







As the drawing suggests, make good and sure that you're only using ONE phase.  In other words, don't put the switch on one phase and the timer on the other, wire them together, and expect them to work.

Call an industrial electrician if you're not sure about doing this yourself; I wouldn't expect a residential one to understand this.  (When I worked for an industrial controls company, some customers hired residential guys to do the wiring.  I was very impressed with them...the wrong way.)



Alternatively, most residential timers have provisions for manual override, as long as you can access the timer itself.  But judging by your question, it seems that you want to bury the timer and forget about it.