Replace Flutter app with native SwiftUI rewrite (iOS 26)

Complete ground-up rewrite in SwiftUI targeting iOS 26. Drops the Flutter/Dart
codebase entirely in favour of a lean native app with no third-party dependencies.

Features shipped:
- Bookmark list with pagination, pull-to-refresh, swipe delete/archive
- Add bookmark form + iOS share extension (zero-tap save from any app)
- Tags tab — all tags sorted by count, tap to browse filtered bookmarks
- Native search tab (Tab role: .search) with instant client-side filtering
- AI enrichment via OpenRouter (google/gemini-2.0-flash-lite-001): auto-summary
  and tag generation, semantic search, smart collections
- Settings: linkding server config, OpenRouter API key
- App Groups for credential sharing between main app and share extension
- Swift 6 strict concurrency throughout (@Observable, @MainActor)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Marks/Views/AddBookmarkView.swift

@@ -0,0 +1,88 @@
+import SwiftUI
+
+struct AddBookmarkView: View {
+    @Bindable var viewModel: BookmarksViewModel
+    @Environment(\.dismiss) private var dismiss
+
+    @State private var url = ""
+    @State private var title = ""
+    @State private var tagsText = ""
+    @State private var isSaving = false
+    @State private var error: String?
+
+    var body: some View {
+        NavigationStack {
+            Form {
+                Section {
+                    TextField("https://", text: $url)
+                        .keyboardType(.URL)
+                        .textInputAutocapitalization(.never)
+                        .autocorrectionDisabled()
+                } header: {
+                    Text("URL")
+                }
+
+                Section {
+                    TextField("Optional", text: $title)
+                } header: {
+                    Text("Title")
+                }
+
+                Section {
+                    TextField("comma separated", text: $tagsText)
+                        .textInputAutocapitalization(.never)
+                        .autocorrectionDisabled()
+                } header: {
+                    Text("Tags")
+                } footer: {
+                    Text("Separate tags with commas")
+                }
+
+                if let error {
+                    Section {
+                        Text(error)
+                            .foregroundStyle(.red)
+                            .font(.footnote)
+                    }
+                }
+            }
+            .navigationTitle("Add Bookmark")
+            .navigationBarTitleDisplayMode(.inline)
+            .toolbar {
+                ToolbarItem(placement: .cancellationAction) {
+                    Button("Cancel") { dismiss() }
+                }
+                ToolbarItem(placement: .confirmationAction) {
+                    Button("Save") { save() }
+                        .disabled(url.trimmingCharacters(in: .whitespaces).isEmpty || isSaving)
+                        .overlay {
+                            if isSaving { ProgressView().scaleEffect(0.7) }
+                        }
+                }
+            }
+        }
+    }
+
+    private func save() {
+        var urlString = url.trimmingCharacters(in: .whitespaces)
+        if !urlString.hasPrefix("http://") && !urlString.hasPrefix("https://") {
+            urlString = "https://" + urlString
+        }
+        guard URL(string: urlString) != nil else {
+            error = "Invalid URL"
+            return
+        }
+        let tags = tagsText.split(separator: ",").map { $0.trimmingCharacters(in: .whitespaces) }.filter { !$0.isEmpty }
+        isSaving = true
+        error = nil
+        Task {
+            do {
+                try await viewModel.addBookmark(url: urlString, title: title.trimmingCharacters(in: .whitespaces), tags: tags)
+                dismiss()
+            } catch {
+                self.error = error.localizedDescription
+                isSaving = false
+            }
+        }
+    }
+}