After I wanted to say "pretty generic alu, can be anything" with those filed welds it is at least something better, not many take the effort even with bigger brands' lower end models. I don't think this info will get you far, it shows similarities to Cannondale CAAD 2 (like several others from the mid/late 90s), but it is not that. Did you drill the holes into the downtubes, or it came with those unknown for me downtube shifters?
Another question, rather for my personal curiosity, was this frame media blasted?

selected pic assist: