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/Info.plist

@@ -0,0 +1,28 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+    <key>CFBundleDisplayName</key>
+    <string>Marks</string>
+    <key>CFBundleExecutable</key>
+    <string>$(EXECUTABLE_NAME)</string>
+    <key>CFBundleIdentifier</key>
+    <string>$(PRODUCT_BUNDLE_IDENTIFIER)</string>
+    <key>CFBundleName</key>
+    <string>$(PRODUCT_NAME)</string>
+    <key>CFBundlePackageType</key>
+    <string>$(PRODUCT_BUNDLE_PACKAGE_TYPE)</string>
+    <key>CFBundleShortVersionString</key>
+    <string>1.0</string>
+    <key>CFBundleVersion</key>
+    <string>1</string>
+    <key>LSRequiresIPhoneOS</key>
+    <true/>
+    <key>UILaunchScreen</key>
+    <dict/>
+    <key>UISupportedInterfaceOrientations</key>
+    <array>
+        <string>UIInterfaceOrientationPortrait</string>
+    </array>
+</dict>
+</plist>