* Settings Page: add warning for unsaved settings
## Issue
When entering Settings Page, sync-loop is disable until user exist Settings Page. If browser is closed, changes will be lost.
## Change
Add the usual browser-level modal popup.
Note that all modern browsers have stopped supporting customized messages, but I still left the message there for clarity. Tried to use our own toast for it, but the handler locks all GUI until it is serviced.
* app: remove unused props
* app: use lighter selectors
When all we need is to know if something exists or their count, use the ID version instead of the url/claim version to avoid the heavy transformation.
08ebedb4cc