backend impl and some of the UI for ephemeral item support
more to come, this is just a WIP so far
Consolidate client-side ephemeral fee logic in FeeButton components for easier reuse
* update the update_item function to handle the case where an item was not
ephemeral, but now is, so we charge the user accordingly
* introduce `hasDeleteCommand` for a better logical abstraction for some use cases in the code
* introduce `EPHEMERAL_FEE_SATS` which is derived from `EPHEMERAL_FEE_MSATS`, so we don't
have to the same calculation over and over
Remove fees for ephemeral items
* remove unused markdownField prop in FeeButton
* remove empty migration
minor code cleanup
Centralize delete item by author code to reduce duplication
1d394bebe1