Speed up landing screen: drop per-PR enrichment + add inbox cache; bump to 2.1

The inbox was slow because it enriched every PR with CI runs + reviews (2
extra API calls per PR, sequential). Drop that from the list — CI/review
status now shows only in the PR detail screen. Add a disk cache so the landing
screen renders instantly from the last load, then refreshes in the background
and keeps the cached list on network failure. Bump to 2.1.

GiteaPR/Views/InboxView.swift

@@ -41,7 +41,10 @@ struct InboxView: View {
             }
             .task { await vm.load() }
             .overlay {
-                if vm.isLoading {
+                // 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()
                 }
             }
@@ -74,10 +77,6 @@ struct PRRowView: View {
                     Text("#\(row.pr.number)")
                         .font(.subheadline.weight(.bold))
                         .foregroundColor(.secondary)
-                    CICircle(status: row.ciStatus)
-                    if row.reviewState != .unknown {
-                        ReviewBadge(state: row.reviewState)
-                    }
                     if row.pr.draft == true {
                         Text("Draft")
                             .font(.caption2)