Add Share Extension for importing recipes via URL

Adds a Share Extension so users can share URLs from Safari (or any app)
to open the main app with the ImportURLSheet pre-filled. Uses a custom
URL scheme (nextcloud-cookbook://) as the bridge between the extension
and the main app.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Nextcloud Cookbook iOS Client/Nextcloud_Cookbook_iOS_ClientApp.swift

@@ -15,6 +15,8 @@ struct Nextcloud_Cookbook_iOS_ClientApp: App {
     @AppStorage("language") var language = Locale.current.language.languageCode?.identifier ?? "en"
     @AppStorage("appearanceMode") var appearanceMode = AppearanceMode.system.rawValue
 
+    @State private var pendingImportURL: String?
+
     var colorScheme: ColorScheme? {
         switch appearanceMode {
         case AppearanceMode.light.rawValue: return .light
@@ -29,7 +31,7 @@ struct Nextcloud_Cookbook_iOS_ClientApp: App {
                 if onboarding {
                     OnboardingView()
                 } else {
-                    MainView()
+                    MainView(pendingImportURL: $pendingImportURL)
                 }
             }
             .preferredColorScheme(colorScheme)
@@ -39,6 +41,16 @@ struct Nextcloud_Cookbook_iOS_ClientApp: App {
                 .init(identifier: language ==
                       SupportedLanguage.DEVICE.rawValue ? (Locale.current.language.languageCode?.identifier ?? "en") : language)
             )
+            .onOpenURL { url in
+                guard !onboarding else { return }
+                guard url.scheme == "nextcloud-cookbook",
+                      url.host == "import",
+                      let components = URLComponents(url: url, resolvingAgainstBaseURL: false),
+                      let recipeURL = components.queryItems?.first(where: { $0.name == "url" })?.value,
+                      !recipeURL.isEmpty
+                else { return }
+                pendingImportURL = recipeURL
+            }
         }
     }
 }