- `filteredSubscriptions` was running the filter code whether or not it actually required filtering, because the `!subscriptionFilter` logic is placed in the predicate. While it is a clean one-liner, it is slow when the subs list is huge.
- While at it, moved the code into `getSubscriptionSection` to isolate things.
- The sidebar was resolving the entire subs list, which is super slow for a list of 500+. Since we now have a "Manage Subscriptions" page, just batch-resolve the N visible subs.
- TODO: the code should probably be moved from 'app' to 'sideNavigate'.
