All of our gear was destroyed, but somehow she is still fully stocked? Obviously the entire Red War was an inside job. Tess no doubt gave them access to the city's defense grid, and then quietly slipped away while the vanguard ran around with their thumbs up their butts.
It was clearly all so that she could sell more useless cosmetics to the poor, deprived guardians.
Technically as far as I know she doesn’t have anything that she had. And she’s constantly getting more from fenchurch so it’d make sense she’d still have stuff.