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>

project.yml

@@ -0,0 +1,61 @@
+name: Marks
+
+options:
+  bundleIdPrefix: com.magicive
+  deploymentTarget:
+    iOS: "26.0"
+  xcodeVersion: "16.3"
+  createIntermediateGroups: true
+
+settings:
+  base:
+    SWIFT_VERSION: "6.0"
+    DEVELOPMENT_TEAM: AE5DZKJHGN
+    CODE_SIGN_STYLE: Automatic
+    IPHONEOS_DEPLOYMENT_TARGET: "26.0"
+    ENABLE_PREVIEWS: YES
+
+schemes:
+  Marks:
+    build:
+      targets:
+        Marks: all
+        ShareExtension: all
+    run:
+      config: Debug
+    test:
+      config: Debug
+    profile:
+      config: Release
+    analyze:
+      config: Debug
+    archive:
+      config: Release
+
+targets:
+  Marks:
+    type: application
+    platform: iOS
+    sources:
+      - path: Marks
+    settings:
+      base:
+        PRODUCT_BUNDLE_IDENTIFIER: com.magicive.marks
+        INFOPLIST_FILE: Marks/Info.plist
+        CODE_SIGN_ENTITLEMENTS: Marks/Marks.entitlements
+        ASSETCATALOG_COMPILER_APPICON_NAME: AppIcon
+    dependencies:
+      - target: ShareExtension
+
+  ShareExtension:
+    type: app-extension
+    platform: iOS
+    sources:
+      - path: ShareExtension
+    settings:
+      base:
+        PRODUCT_BUNDLE_IDENTIFIER: com.magicive.marks.ShareExtension
+        INFOPLIST_FILE: ShareExtension/Info.plist
+        CODE_SIGN_ENTITLEMENTS: ShareExtension/ShareExtension.entitlements
+        SKIP_INSTALL: YES
+        APPLICATION_EXTENSION_API_ONLY: YES