Errr... none of the above?
I pronounce it "Teh", a bit like "Terrible" if you were to stop talking after the first 2 letters.
Effectively, it becomes "Te' Forum"
Like 'eh', but with a 't' in front of it. So shorter than 'tear' (as in rip) and an more abrupt ending.
Sounding more like 'bleh', come to think of it.
Agreed, it's pronounced how it's spelt.
Teh to rhyme with yeah.