Add Gear Compare API

[flyxiv]

Refactored frontend code so that it's easier to make two equipment sets. Time to add gear compare

[flyxiv]

Prototype Design

• I also want to add an arrow to copy one gearset to the other gearset.

[flyxiv]

So easy to implement with the refactors.

Let's add copy arrows

[flyxiv]

UIs for best partner and stat weights also finished. Tommorow we work on Rust backend again.

[flyxiv]

api added.