fix(backup): hard-lock status area to 66pt on all pages for consistent stat alignment

Replace opacity(0) approach with a ZStack(.frame(height:66)) container.
ZStack is empty on pages 1/2 but still allocates exactly 66pt, so the
page indicator and stats strip sit at the same absolute Y on every page.

Co-Authored-By: Kutesir <kutesir@provoc.ug>
Co-Authored-By: Sentry <sentry@provoc.ug>

Features/Backup/BackupView.swift

@@ -681,15 +681,20 @@ struct BackupView: View {
             }
             .padding(.bottom, 4)
 
+            // Fixed-height container — guarantees identical Y for all pages
+            ZStack(alignment: .top) {
+                if ringPage == 0 {
+                    VStack(spacing: 0) {
                         cascadingArrows
                             .frame(height: 16)
                             .padding(.bottom, 8)
-                .opacity(ringPage == 0 ? 1 : 0)
-
                         circleStatusRow
                             .padding(.horizontal, AppTheme.hPad)
                             .padding(.bottom, 10)
-                .opacity(ringPage == 0 ? 1 : 0)
+                    }
+                }
+            }
+            .frame(height: 66)
         }
         // Pull zone floats above the ring on all pages
         .overlay(alignment: .top) {