Merge success animation + auto-return to landing page; bump to 3.0

On a successful merge, show a brief full-screen green checkmark animation
('Merged'), then automatically pop the PR detail view back to the landing
page. MergeSheet now calls an onSuccess callback; PRDetailView shows the
overlay and dismisses after ~1.2s. Bump to 3.0.

GiteaPR/Detail/PRDetailView.swift

@@ -2,12 +2,14 @@ import SwiftUI
 
 struct PRDetailView: View {
     @StateObject private var vm: PRDetailViewModel
+    @Environment(\.dismiss) private var dismiss
     @State private var selectedTab: DetailTab = .overview
     @State private var showCommentSheet = false
     @State private var showMergeSheet = false
     @State private var showCloseConfirm = false
     @State private var showRerunConfirm: ActionRun?
     @State private var requestChangesMode = false
+    @State private var showMergeSuccess = false
 
     enum DetailTab: String, CaseIterable, Identifiable {
         case overview = "Overview"
@@ -56,6 +58,7 @@ struct PRDetailView: View {
             Button("OK", role: .cancel) {}
         } message: { Text(vm.errorMessage ?? "") }
         .overlay { if vm.busyMessage != nil { busyOverlay } }
+        .overlay { if showMergeSuccess { mergeSuccessOverlay } }
         .confirmationDialog("Close this PR?", isPresented: $showCloseConfirm, titleVisibility: .visible) {
             Button("Close", role: .destructive) { Task { await vm.setState("closed") } }
             Button("Cancel", role: .cancel) {}
@@ -65,7 +68,19 @@ struct PRDetailView: View {
                          mode: requestChangesMode ? .requestChanges : .comment)
                 .onDisappear { requestChangesMode = false }
         }
-        .sheet(isPresented: $showMergeSheet) { MergeSheet(vm: vm) }
+        .sheet(isPresented: $showMergeSheet) {
+            MergeSheet(vm: vm) {
+                // Merge succeeded: show the success animation, then pop back
+                // to the landing page.
+                withAnimation(.spring(response: 0.4, dampingFraction: 0.6)) {
+                    showMergeSuccess = true
+                }
+                Task {
+                    try? await Task.sleep(nanoseconds: 1_200_000_000)
+                    dismiss()
+                }
+            }
+        }
         .confirmationDialog("Re-run workflow?",
                             isPresented: .init(
                                 get: { showRerunConfirm != nil },
@@ -219,4 +234,24 @@ struct PRDetailView: View {
         }
         .ignoresSafeArea()
     }
+
+    /// Full-screen success animation shown briefly after a merge, then the
+    /// view pops back to the landing page.
+    private var mergeSuccessOverlay: some View {
+        ZStack {
+            Color.black.opacity(0.4)
+                .ignoresSafeArea()
+            VStack(spacing: 12) {
+                Image(systemName: "checkmark.circle.fill")
+                    .font(.system(size: 72))
+                    .foregroundColor(.green)
+                    .scaleEffect(showMergeSuccess ? 1 : 0.3)
+                    .opacity(showMergeSuccess ? 1 : 0)
+                Text("Merged")
+                    .font(.title2.weight(.semibold))
+                    .foregroundColor(.white)
+            }
+        }
+        .transition(.opacity)
+    }
 }