Website should list available architectures for each image

We do this [on the real store](https://blueos.cloud/docs/latest/usage/advanced/#extensions-manager), and it would be helpful for users (and developers) to be able to know in advance if a build is available for their architecture.

In BlueOS the determination is with [a set of the architectures of all the images](https://github.com/bluerobotics/BlueOS/blob/489b2890d7c3a3550145849251e538140cf0c7f3/core/frontend/src/components/kraken/cards/StoreExtensionCard.vue#L175-L183), which are then listed on the Extension card.