seedling discoloration, leaning toward center, brown perlite despite no nutrients so far

Sieht normal und gesund aus. Wenn du merkst das er länger wird must du das Licht näher machen oder sie intensität etwas verstärken. Sonst sieht sie top aus viel erfolg

They will be fine. Just google a vpd chart and dial that in. You have nothing to worry about. Happy growing

Plants bend toward the light, so that's fine. As far as intensity, use the resulting internode development (stem between nodes) to guage intensity and make adjustments. If too tight, reduce. If too lanky, increase. Take note when you find that goldilocks zone that's just right. umol/s of PAR can mean different things in different environments, as far as how much a plant can take per 24 hours. Seedlings will need less than a mature plant, initially, but will quickly ask for me (see 'too much stretch' above). So, what other people can do is not necessarily what is right for your local variables. VPD is a big deal in this regard. You can definitely give more light per day when the VPD is in a decent range - not too high, not too low... just right. There's a theme here, and it takes a little bit of trial and error before you find it. Also, use properly sized seedling pots in future. Potting up does not cause shock. That is a myth that gets repeated ad nauseum and simply not true. The pita to water a tiny plant in a big pot and the increased probability of problems that result are reason enough to just do it in an orthodox way... use appropriately sized pots and pot up to larger ones as needed. Your rootzone and results will thank you.