Eliminate useEffect-based synchronization of React Query server state
into React Context, which caused extra renders, state drift, and
incorrect loading/empty states on the /explore/apps page.
- Remove installedApps, isFetchingInstalledApps, and
controlUpdateInstalledApps from ExploreContext (dead code + anti-pattern)
- Sidebar and InstalledApp now consume useGetInstalledApps() directly
- Use isLoading (not isPending) for conditionally-enabled queries to
avoid permanent loading state when query is disabled
- Derive hasEditPermission during render instead of via useEffect
- Replace FC type annotations with const arrow functions
- Add return type to fetchInstalledAppList
- Update all related unit and integration tests
