activeSyncCount/isSyncing() in useFeeds.js already refcounted both boot
reload (fetchData) and manual sync() but wasn't reactive. Make it a ref
+ computed and expose it so AppNav can render a small spinner next to
the feed filter whenever a sync is in flight.
The spinner sits outside the filter's own v-if so it also shows during
a manual sync from pages other than /feeds, and its box is always
reserved (visibility toggle, not v-if) so the one-time --app-nav-height
measurement stays correct.
The Add RSS modal is now opened from a button directly above the feed
list in AdminFeeds.vue instead of the hamburger menu, so feed creation
lives alongside the rest of feed management. AppNav.vue no longer
renders it.
AddUrl.vue emits an `added` event on a successful save; AdminFeeds.vue
listens for it and reloads its feed list, so a newly added feed shows
up immediately without leaving the admin page.
Also fixes a bug this move surfaced: the modal's "Close" button had no
`type`, so inside the form it defaulted to type="submit" — clicking
Close on a filled-in form silently created the feed.
mathias