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/Services/LinkdingAPI.swift

@@ -0,0 +1,123 @@
+import Foundation
+
+enum APIError: Error, LocalizedError {
+    case badStatus(Int)
+    case invalidUrl
+    case noData
+
+    var errorDescription: String? {
+        switch self {
+        case .badStatus(let code): "Server returned \(code)"
+        case .invalidUrl: "Invalid server URL"
+        case .noData: "No data received"
+        }
+    }
+}
+
+actor LinkdingAPI {
+    private let config: ServerConfig
+    private let session: URLSession
+    private let decoder: JSONDecoder
+
+    init(config: ServerConfig) {
+        self.config = config
+        self.session = URLSession.shared
+        let d = JSONDecoder()
+        d.dateDecodingStrategy = .custom { decoder in
+            let s = try decoder.singleValueContainer().decode(String.self)
+            let f = ISO8601DateFormatter()
+            f.formatOptions = [.withInternetDateTime, .withFractionalSeconds]
+            if let date = f.date(from: s) { return date }
+            f.formatOptions = [.withInternetDateTime]
+            if let date = f.date(from: s) { return date }
+            throw DecodingError.dataCorrupted(.init(codingPath: decoder.codingPath, debugDescription: "Bad date: \(s)"))
+        }
+        self.decoder = d
+    }
+
+    private func makeUrl(path: String, queryItems: [URLQueryItem] = []) throws -> URL {
+        var components = URLComponents()
+        components.scheme = config.useHttps ? "https" : "http"
+        components.host = config.host
+        components.port = config.port
+        components.path = config.path.isEmpty ? path : config.path + path
+        if !queryItems.isEmpty { components.queryItems = queryItems }
+        guard let url = components.url else { throw APIError.invalidUrl }
+        return url
+    }
+
+    private func authorizedRequest(url: URL, method: String = "GET", body: Data? = nil) -> URLRequest {
+        var req = URLRequest(url: url)
+        req.httpMethod = method
+        req.setValue("Token \(config.token)", forHTTPHeaderField: "Authorization")
+        if let body {
+            req.setValue("application/json", forHTTPHeaderField: "Content-Type")
+            req.httpBody = body
+        }
+        return req
+    }
+
+    func fetchBookmarks(search: String = "", offset: Int = 0, limit: Int = 50) async throws -> BookmarkResponse {
+        var items: [URLQueryItem] = [
+            .init(name: "limit", value: "\(limit)"),
+            .init(name: "offset", value: "\(offset)")
+        ]
+        if !search.isEmpty { items.append(.init(name: "q", value: search)) }
+        let url = try makeUrl(path: "/api/bookmarks/", queryItems: items)
+        let (data, response) = try await session.data(for: authorizedRequest(url: url))
+        guard (response as? HTTPURLResponse)?.statusCode == 200 else {
+            throw APIError.badStatus((response as? HTTPURLResponse)?.statusCode ?? 0)
+        }
+        return try decoder.decode(BookmarkResponse.self, from: data)
+    }
+
+    func fetchBookmarksFromUrl(_ urlString: String) async throws -> BookmarkResponse {
+        guard let url = URL(string: urlString) else { throw APIError.invalidUrl }
+        let (data, _) = try await session.data(for: authorizedRequest(url: url))
+        return try decoder.decode(BookmarkResponse.self, from: data)
+    }
+
+    func createBookmark(_ create: BookmarkCreate) async throws -> Bookmark {
+        let body = try JSONEncoder().encode(create)
+        let url = try makeUrl(path: "/api/bookmarks/")
+        let (data, response) = try await session.data(for: authorizedRequest(url: url, method: "POST", body: body))
+        guard (response as? HTTPURLResponse)?.statusCode == 201 else {
+            throw APIError.badStatus((response as? HTTPURLResponse)?.statusCode ?? 0)
+        }
+        return try decoder.decode(Bookmark.self, from: data)
+    }
+
+    func updateBookmark(id: Int, tagNames: [String]) async throws -> Bookmark {
+        let body = try JSONEncoder().encode(["tag_names": tagNames])
+        let url = try makeUrl(path: "/api/bookmarks/\(id)/")
+        let (data, response) = try await session.data(for: authorizedRequest(url: url, method: "PATCH", body: body))
+        guard (response as? HTTPURLResponse)?.statusCode == 200 else {
+            throw APIError.badStatus((response as? HTTPURLResponse)?.statusCode ?? 0)
+        }
+        return try decoder.decode(Bookmark.self, from: data)
+    }
+
+    func deleteBookmark(id: Int) async throws {
+        let url = try makeUrl(path: "/api/bookmarks/\(id)/")
+        let (_, response) = try await session.data(for: authorizedRequest(url: url, method: "DELETE"))
+        guard (response as? HTTPURLResponse)?.statusCode == 204 else {
+            throw APIError.badStatus((response as? HTTPURLResponse)?.statusCode ?? 0)
+        }
+    }
+
+    func archiveBookmark(id: Int) async throws {
+        let url = try makeUrl(path: "/api/bookmarks/\(id)/archive/")
+        let (_, response) = try await session.data(for: authorizedRequest(url: url, method: "POST"))
+        guard let code = (response as? HTTPURLResponse)?.statusCode, code == 200 || code == 204 else {
+            throw APIError.badStatus((response as? HTTPURLResponse)?.statusCode ?? 0)
+        }
+    }
+
+    func verifyConnection() async throws {
+        let url = try makeUrl(path: "/api/bookmarks/", queryItems: [.init(name: "limit", value: "1")])
+        let (_, response) = try await session.data(for: authorizedRequest(url: url))
+        guard (response as? HTTPURLResponse)?.statusCode == 200 else {
+            throw APIError.badStatus((response as? HTTPURLResponse)?.statusCode ?? 0)
+        }
+    }
+}