Remove in-list spinner + add monitored-repos setting; bump to 2.3

- Remove the in-list loading wheel overlay; the landing page just shows the
  cached list or the 'No open PRs' screen.
- Add a 'Monitored repos' setting (Settings > Inbox) that limits the inbox to
  specific repos, cutting the number of API calls dramatically. Empty =
  monitor all accessible repos. Bump to 2.3.

GiteaPR/Views/InboxView.swift

@@ -52,14 +52,6 @@ struct InboxView: View {
                 didInitialLoad = true
                 await vm.load()
             }
-            .overlay {
-                // Only show a spinner when there's nothing cached to display
-                // yet; with a cache the list renders instantly and refreshes
-                // in the background.
-                if vm.isLoading && vm.displayedRows.isEmpty {
-                    ProgressView()
-                }
-            }
             .alert("Error", isPresented: .init(
                 get: { vm.errorMessage != nil },
                 set: { if !$0 { vm.errorMessage = nil } })) {