There are basically two approaches to this. A good hardtail 29'er mountain bike with quality fork and components will run you about $1000. That should be ideal for anything other than highly technical trail riding. It will also work well for commuting.

Option A: Commute on hardtail 29er.

Option B: Commute on a cheap bike (<$400), buy a quality bike for trails. Main advantage is that the commute bike is cheap and easily replaced in the event of accident/theft.

IMO the only way you can really go wrong is spending $500-800 on a hybrid/city bike. Ultimately, those bikes aren't suitable for real trail riding and are overkill for a 1.5mi commute.

Most of the lower tier mountain bikes are meant for trail riding, on semi-paved paths. For any serious MTB riding you want a air suspension fork, which requires moving up to better bikes (and ideally Deore+ level components). Most coil spring forks are optimized for heavier riders, at your weight you won't be able to compress a coil fork. Even ones with adjustable pre-load won't go low enough without changing to a different coil spring, which will cost extra. Depending on the bike storage situation, there's nothing wrong with getting a cheap bike to start, then buying a better bike for trail riding.

For reference:
Shimano components: Altus/Acera/Claris/Sora - city and light trail bikes, entry level mountain/road components (usually 8 or 9 speed).
Deore/SLX/XT/XTR -- MTB components in order of quality (all are 10-speed). SLX is basically just as good as XTR, just heavier.
Tiagra/105/Ultegra/Dura-Ace -- Road components. Similarly, 105 is almost as good as Dura-Ace, just heavier. 105 and up are 11-speed.