Merge spinner + swipeable PR sections; bump to 3.1

- MergeSheet: show a spinner in the toolbar while the merge is confirming/
  rejecting, lock Cancel and interactive dismissal during the request, and
  prevent double-taps.
- PR detail: replace the ScrollView-switch with a page-style TabView so you
  can swipe left/right to change sections (iOS 26 style); bottom bar taps
  still select. Make DetailTab Hashable. Bump to 3.1.

GiteaPR.xcodeproj/project.pbxproj

@@ -187,7 +187,7 @@
 			buildSettings = {
 				ASSETCATALOG_COMPILER_APPICON_NAME = AppIcon;
 				CODE_SIGN_STYLE = Automatic;
-				CURRENT_PROJECT_VERSION = 21;
+				CURRENT_PROJECT_VERSION = 22;
 				DEVELOPMENT_TEAM = "";
 				GENERATE_INFOPLIST_FILE = YES;
 				INFOPLIST_KEY_CFBundleDisplayName = "GiteaPR";
@@ -197,7 +197,7 @@
 					"$(inherited)",
 					"@executable_path/Frameworks",
 				);
-				MARKETING_VERSION = 3.0;
+				MARKETING_VERSION = 3.1;
 				PRODUCT_BUNDLE_IDENTIFIER = com.bueso.giteapr;
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SWIFT_EMIT_LOC_STRINGS = YES;
@@ -211,7 +211,7 @@
 			buildSettings = {
 				ASSETCATALOG_COMPILER_APPICON_NAME = AppIcon;
 				CODE_SIGN_STYLE = Automatic;
-				CURRENT_PROJECT_VERSION = 21;
+				CURRENT_PROJECT_VERSION = 22;
 				DEVELOPMENT_TEAM = "";
 				GENERATE_INFOPLIST_FILE = YES;
 				INFOPLIST_KEY_CFBundleDisplayName = "GiteaPR";
@@ -221,7 +221,7 @@
 					"$(inherited)",
 					"@executable_path/Frameworks",
 				);
-				MARKETING_VERSION = 3.0;
+				MARKETING_VERSION = 3.1;
 				PRODUCT_BUNDLE_IDENTIFIER = com.bueso.giteapr;
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SWIFT_EMIT_LOC_STRINGS = YES;

GiteaPR/Detail/PRDetailView.swift

@@ -11,7 +11,7 @@ struct PRDetailView: View {
     @State private var requestChangesMode = false
     @State private var showMergeSuccess = false
 
-    enum DetailTab: String, CaseIterable, Identifiable {
+    enum DetailTab: String, CaseIterable, Identifiable, Hashable {
         case overview = "Overview"
         case conversation = "Conversation"
         case files = "Files"
@@ -103,14 +103,20 @@ struct PRDetailView: View {
         VStack(spacing: 0) {
             header(pr)
 
-            ScrollView {
-                switch selectedTab {
-                case .overview: OverviewTab(pr: pr)
-                case .conversation: ConversationTab(vm: vm)
-                case .files: FilesTab(vm: vm)
-                case .checks: ChecksTab(vm: vm, onRerun: { showRerunConfirm = $0 })
-                }
+            // Page-style TabView gives iOS-native swipe-to-change between
+            // sections (matching iOS 26), while the bottom bar taps select.
+            TabView(selection: $selectedTab) {
+                OverviewTab(pr: pr)
+                    .tag(DetailTab.overview)
+                ConversationTab(vm: vm)
+                    .tag(DetailTab.conversation)
+                FilesTab(vm: vm)
+                    .tag(DetailTab.files)
+                ChecksTab(vm: vm, onRerun: { showRerunConfirm = $0 })
+                    .tag(DetailTab.checks)
             }
+            .tabViewStyle(.page(indexDisplayMode: .never))
+            .ignoresSafeArea(edges: .bottom)
 
             bottomTabBar
         }

GiteaPR/Detail/Sheets.swift

@@ -65,6 +65,7 @@ struct MergeSheet: View {
     @ObservedObject var vm: PRDetailViewModel
     @Environment(\.dismiss) private var dismiss
     @State private var method = "merge"
+    @State private var isMerging = false
     /// Called when the merge succeeds, so the parent can show the success
     /// animation and pop back to the landing page.
     var onSuccess: () -> Void = {}
@@ -118,20 +119,33 @@ struct MergeSheet: View {
             .navigationBarTitleDisplayMode(.inline)
             .toolbar {
                 ToolbarItem(placement: .cancellationAction) {
-                    Button("Cancel") { dismiss() }
+                    if isMerging {
+                        // No cancel while a merge is in flight.
+                    } else {
+                        Button("Cancel") { dismiss() }
+                    }
                 }
                 ToolbarItem(placement: .confirmationAction) {
-                    Button("Merge") { performMerge() }
-                        .disabled(SettingsStore.shared.mergeGateMode == .block
-                                  && vm.ciStatus == .failure)
+                    if isMerging {
+                        // Spinner while the merge is confirming/rejecting.
+                        ProgressView()
+                    } else {
+                        Button("Merge") { performMerge() }
+                            .disabled(SettingsStore.shared.mergeGateMode == .block
+                                      && vm.ciStatus == .failure)
+                    }
                 }
             }
+            .interactiveDismissDisabled(isMerging)
         }
     }
 
     private func performMerge() {
+        guard !isMerging else { return }
+        isMerging = true
         Task {
             let success = await vm.merge(method: method)
+            isMerging = false
             if success {
                 dismiss()
                 onSuccess()